JPS6313264A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

PURPOSE:To increase charge-discharge cycle performance by forming a negative electrode with main alkali metal and a metal structure comprising a submetal, and electrochemically alloying the submetal with the alkali metal. CONSTITUTION:A negative electrode 3 is formed in such a way that an alkali metal plate 3a, a metal structure 3b and an alkali metal plate 3c are placed inside a negative can 1, and lithium as the alkali metal and aluminium which is main metal of the metal structure are electrochemically alloyed under the existing of electrolyte. Powdering or breaking of the negative electrode 3 is prevented and charge-discharge performance is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to improvement of its negative electrode.

[Conventional technology]

The conventional technology and problems associated with non-aqueous electrolyte secondary batteries will be explained using lithium secondary batteries, which are the most popular among non-aqueous electrolyte secondary batteries, as an example. Two methods were employed. One is to use pure metallic lithium in the form of a plate for the negative electrode, and the other is to use lithium in other materials such as aluminum, as shown in U.S. Pat. No. 4,002,492, for example. It was alloyed with other metals.

In the former method, in which metallic lithium is used as it is in the form of a plate, lithium precipitates in the form of dendrites (dendritic branches) during charging, and this dendrite-like lithium is very active and reacts with the electrolyte, or breaks off from the base and falls off. However, there was a problem in that it could no longer be used for charge/discharge reactions, resulting in poor charge/discharge cycle characteristics. In addition, the dendrite-like lithium grows through repeated charging and discharging, penetrates the separator that separates the positive electrode and negative electrode, and comes into contact with the positive electrode, causing an internal short circuit and causing the battery to lose its function. In addition, the latter method of alloying lithium with aluminum etc. and using it for the negative electrode causes lithium to diffuse into the aluminum crystal through an electrochemical alloying reaction between lithium and aluminum during charging, causing the lithium to form a dendrite shape. This method attempts to suppress the reaction with electrolytes and suppress dendrite growth by reducing the amount of lingering, but although it has been found to be effective in suppressing dendrites, for example, J.

0, Bosenhard J, Electroanal
, Chem, +94+77 (1978), due to repeated charging and discharging, the negative electrode becomes finer or collapses, making it impossible to obtain sufficient electron conduction between metal particles, resulting in rapid deterioration of battery performance. was there.

Therefore, as a method to suppress the miniaturization or collapse of such negative electrodes, aluminum is replaced with magnesium,
It has been proposed to alloy it with other metals such as boron and gallium (for example, JP-A-60-86760).

However, according to the study results of the present inventors, when aluminum is alloyed with other metals as described above, the alloying area is extremely limited (for example, in the case of an aluminum-boron alloy, boron is (If it is less than 1% by weight, it cannot be processed into a thin plate shape), and although the charge-discharge cycle characteristics are improved compared to aluminum alone, it is not sufficient, and satisfactory results were not necessarily obtained.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems of the conventional products having poor charge-discharge cycle characteristics and the problem that the negative electrode becomes fine or collapses due to repeated charging and discharging. The purpose is to provide secondary batteries.

[Means for solving problems]

In the present invention, a main metal M and a sub-metal M' that are alloyed with an alkali metal are dispersed without alloying to form a structure, and the alkali metal is electrochemically alloyed with this metal structure to form a negative electrode. By doing so, when the negative electrode causes a charge/discharge reaction, the subsidiary metal M' acts as a binder and a conductive agent in the negative boundary, thereby solving the problems of conventional products as described above, and improving the charge/discharge cycle characteristics. This provides an excellent non-aqueous electrolyte secondary battery.

This is explained in detail as follows.

For example, when two types of metals consisting of Ml and M2, both of which are alloyed with lithium, are used for the negative electrode, the charge/discharge reaction of the negative electrode is expressed by the following equations (1) and (2).

Ml +xLi"+xe"", = M 1L i x
(1) M2+yLi"+ye'-=M2Liy
f2) The reactions of formulas (1) and (2) above may occur simultaneously and competitively, but in most cases, one reaction occurs preferentially, followed by the other. Therefore,
If we consider a case where the reaction of formula (1) occurs preferentially and the reaction of formula (2) follows, the reaction of formula (2) practically does not occur. In addition, if metal M2 is a metal that does not alloy with lithium (Li), such as nickel, (2
) reaction does not occur at all.

In this way, if the reaction of equation (2) follows the reaction of equation (11), or if the reaction of equation (2) does not occur at all, gold MM2 is formed by metal M1 being electrochemically alloyed with lithium. , when lithium is occluded inside it, or when lithium is eluted from the inside as ions into the electrolyte (due to this lithium intercalation and elution into the electrolyte, the metal M1 repeats volumetric expansion and contraction, and the negative electrode becomes fine). The binder that binds gold 1i!M1 and the metal M
Acts as a conductive agent to ensure electron conduction between 1 and the negative current collector.As a result, the negative electrode is prevented from becoming fine and disintegrated, and electronic conductivity is ensured, so even after repeated charging and discharging, the negative electrode remains stable. Deterioration is suppressed, and therefore charge-discharge cycle characteristics are improved compared to conventional products.

As yet another example, a metal M that alloys with an alkali metal
Considering the case where three types of metals are used: 3 and M4, and a metal M5 that does not alloy with an alkali metal, the charge/discharge reaction of the negative electrode is as shown in the following equations (3) and (4).

M3 +mL t" +me-, =: M3 L im
(31M4 +n L i” +n e-#M4 L
il f41 In this case, the metal MS is the metal M
For the same reason as 2, it acts as a binder and a conductive agent for metals M3 and M4.

In other words, when a metal M that alloys with an alkali metal and a metal M' that does not alloy with an alkali metal are dispersed without being alloyed, the metal M' that does not alloy with an alkali metal during charging and discharging is
It acts as a binder and conductive agent for the metal M that is alloyed with the alkali metal, suppresses the miniaturization or collapse of the negative electrode, and can prevent the deterioration of battery characteristics caused by the miniaturization or collapse.

Also, metals M and M', both of which alloy with alkali metals,
When the metal M is preferentially alloyed without alloying, the other gold g M / acts as a binder and conductive agent and also acts as an alkali ion donor, and the *m of the negative electrode suppresses the formation or collapse of the battery, and prevents the deterioration of battery characteristics caused by the miniaturization or collapse.
Also, by acting as an alkali ion donor, it reduces battery polarization and improves charge-discharge cycle characteristics.

Therefore, the metal M alloyed with the alkali metal in the above
is the main metal, metal M′ is the opening metal, and a structure is formed in which the opening metal M′ is dispersed in the main metal M without being alloyed,
When this metal structure is electrochemically alloyed with an alkali metal and used for a negative electrode, the negative electrode is prevented from becoming finer or disintegrated, and the charge/discharge cycle characteristics can be improved.

The main metal M is required to be alloyable with an alkali metal, but the opening metal M' may be a metal that alloys with an alkali metal or a metal that does not alloy with an alkali metal. In some cases, a metal that is alloyed with an alkali metal is used as a metal structure, so the term "alloying an alkali metal with a metal structure" is used as described above. However, even when a metal that alloys with an alkali metal is used as the opening mud M', the reaction during the charge/discharge cycle is mainly a reaction of the alkali metal alloy of the raw metal IM. The main metal M is usually larger in quantity than the opening metal M', but it is meant as a main metal from the viewpoint of alloying with an alkali metal.

A metal structure in which the main metal M and the opening metal M' are dispersed without alloying can be obtained by, for example, using a plasma spraying method.
It can be formed by welding and the opening member M',
It can also be formed by vapor deposition, sputtering, or the like.

Further, the metal structure can also be formed by powdering the main metal M and the opening metal M' and press-molding the powder.

Examples of alkali metals include lithium (Lt), sodium (Na), potassium (K), and rubidium (Rb).
, cesium (Cs), etc., but lithium is usually used because it is lighter than other alkali metals and can extract a large amount of electricity per unit volume and unit weight.

Examples of the main metal M include aluminum (AI), bismuth (Bi), antimony (Sb), arsenic (As), silicon (Si), gallium (C, a), boron (B), indium (In), and germanium. A simple substance such as (Ge) or an alloy thereof is used.

Examples of the submetal M' include copper (cu) and titanium (Ti).
), iron (Fe), nickel (Ni), tantalum (Ta)
, zirconium (Zr), stainless steel, and other metals that do not alloy with alkali metals, or their alloys, and bismuth, antimony, arsenic, silicon, boron, indium, gallium, which alloy with the above-mentioned alkali metals, Germanium and the like can also be used as secondary metals. The opening mM' is not required to be of one type, but may be two or more types, and a metal that does not alloy with an alkali metal and a metal that alloys with an alkali metal are used as opening mM'. In some cases.

As a preferable combination of raw metal WM and sub metal M', aluminum is used as the main metal M, copper is used as the sub metal M',
Examples include combinations using one or more of titanium, nickel, bismuth, antimony, arsenic, silicon, boron, gallium, and indium.

The ratio of main metal M and sub metal M' is 1:1 to 99 by weight.
:1 is preferable. This is because when the main metal M is less than the above range, the amount of alkali metal that can be alloyed also decreases, the amount of alkali metal used decreases, and the battery capacity decreases. This is because if the amount of the metal M' is less than the above range, the effect of the sub metal M' cannot be sufficiently exhibited.

Further, in configuring the negative electrode, the amount of alkali metal charged, that is, the amount of alkali metal initially alloyed with the metal structure, is 1 out of the total amount of the alkali metal and the main metal M.
The content is preferably 0 to 90 atomic%.

In the battery of the present invention, the alkali metal ion conductive nonaqueous electrolyte includes, for example, 1,2-dimethoxyethane, l
, 2-jethoxyethane, ethylene carbonate, propylene carbonate, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, etc. alone or in a mixed solvent of two or more, for example. LiClO4
, LiPF6, LiAsF6, LiSbF6, LiBF
A liquid organic non-aqueous electrolyte in which one or more types of solutes such as LiB(C6H5)4 and the like are dissolved is used. Further, in order to stabilize the solute such as LiPF6 in the electrolyte, it is also preferable to add a stabilizer such as hexamethylphosphoric triamide.

As the positive electrode active material, for example, titanium disulfide (Ti32)
, molybdenum disulfide (MoS2), molybdenum trisulfide (
MoS3), iron disulfide (F e 32), silconium sulfide (ZrS2), niobium disulfide (Nbs2>, phosphorus trisulfide, kel (NiPS3), vanadium selenide (VSe2), vanadium pentoxide (v205) , 13-oxide vanadium (V50,3), nichrome heoxide (
Cr20B), trichromium hexoxide (Cr3013), lithium cobalt dioxide (L 1co02), Li1+
x V3013 or the like can be used. In particular, titanium disulfide is preferably used because it has a layered crystal structure, has a high diffusion constant for alkali metal ions therein, and allows the charging/discharging reaction on the positive electrode side to proceed smoothly.

Further, the shape of the battery is usually button-shaped, but it can also be used as a cylindrical battery.

〔Example〕

Next, the present invention will be explained in more detail by giving examples.

Example 1 - Two lithium plates with a thickness of 0.1 mm and a diameter of 7.8 mm and an aluminum-copper structure having a structure schematically shown in FIG. 3 with a thickness of 0.3 mm and a diameter of 7.8 mm were used as negative electrode materials. One lithium plate, the aluminum-copper structure, and the other lithium plate were placed in this order in the negative electrode can, and then the battery was assembled according to a conventional method, and lithium was electrochemically added to the above in the presence of an electrolyte. It was alloyed with aluminum in the aluminum-copper structure to form a negative electrode.

In addition, in FIG. 3 showing the aluminum-copper structure,
11 is aluminum, 12 is copper, and 13 is a stainless steel mesh. This aluminum-copper structure uses a stainless steel mesh as a base material, on which aluminum is deposited by plasma spraying, then copper is partially deposited on the aluminum layer by plasma spraying, and then aluminum is deposited on top of the mesh by plasma spraying. Copper and aluminum were welded by plasma spraying, then copper was partially welded onto the aluminum layer by plasma spraying, and this welding of aluminum by plasma spraying and the partial welding of copper by plasma spraying were repeated. The weight ratio of aluminum and copper is 90:10.

A cross-sectional view of a battery having the above negative electrode is shown in FIG.

In the figure, 1 is a negative electrode can made of stainless steel and whose surface is nickel plated, and 2 is a negative electrode current collector made of a stainless steel mesh spot-welded to the inner surface of the negative electrode can 1. 3 is a negative electrode, as shown in FIG. 2, an alkali metal plate (in this example, a lithium plate is used as described above) 381
Metal structure (in this example, an aluminum-copper structure as shown in FIG. 3 is used) 3b and an alkali metal plate (in this example, a lithium plate is used as described above) 3c is placed in the negative electrode can 1 and formed by alloying lithium as an alkali metal and aluminum as the main metal M of the metal structure in the presence of an electrolyte. 4 is a separator made of a microporous polypropylene film, and 5 is an electrolyte absorber made of a polypropylene nonwoven fabric. 6 is titanium disulfide (T i
32) as an active material, a positive electrode made of polytetrafluoroethylene bound with a binder and pressure molded, with a thickness of 0.5 m.
The positive electrode current collector 7 made of a stainless steel mesh is disposed on one surface of the disk. 8 is a stainless steel can with nickel plating on the surface, and 9 is a polypropylene gasket. And this battery has 4-methyl-1,3
- Add 1.0% of LiPF6 to a mixed solvent consisting of 60% by volume of dioxolane, 34.8% of 112-dimethoxyethane and 5.2% by volume of hexamethylphosphoric triamide.
A liquid organic nasal electrolyte dissolved in mol/l is used. The composition of lithium in the negative electrode of this battery is approximately 32 at.
The ris air volume is 8 mA h.

Hexamethylphosphoric triamide in the electrolyte is a stabilizer for stabilizing LiPF6.

Example 2 The same procedure as in Example 1 was used except that instead of the aluminum-copper structure in Example 1, an aluminum-nickel structure was used in which the body portion of the aluminum-copper structure shown in FIG. 3 was replaced with nickel. A non-aqueous electrolyte secondary battery consisting of the following configuration was fabricated.

Example 3 In place of the aluminum-copper structure shown in FIG. 3, an aluminum-gallium-steel structure schematically shown in FIG. 4 (weight ratio of aluminum, gallium, and copper 80:15:5) was used. A non-aqueous electrolyte secondary battery having the same configuration as in Example 1 was manufactured. In addition, in FIG. 4 showing the aluminum-gallium-steel structure 3b, 2) is aluminum,
22 is a gallium mesh, 23 is a copper mesh, and 24 is a stainless steel mesh. This aluminum-gallium-steel structure uses a stainless steel mesh as a base material, on which aluminum is welded by plasma spraying, and then gallium is partially deposited on the aluminum layer by plasma spraying, Aluminum is then deposited by plasma spraying onto the gallium and first aluminum layer, copper is then partially deposited onto the aluminum layer by plasma spraying, aluminum is deposited by plasma spraying, and the aluminum is deposited by plasma spraying. It is formed by appropriately repeating welding by plasma spraying, partial welding of gallium by plasma spraying, partial welding of aluminum by plasma spraying, and partial welding of copper by plasma spraying.

Example 4 The same procedure as Example 1 was used except that instead of the aluminum-copper structure in Example 1, an aluminum-bismuth structure having a structure in which the handle of the aluminum-copper structure shown in FIG. 3 was replaced with bismuth was used. A non-aqueous electrolyte secondary battery having a similar configuration was fabricated.

Comparative Example 1 Two lithium plates with a thickness of 0.1++w and a diameter of 7.8I,
Using an aluminum plate with a thickness of 0.3 mm and a diameter of 7.8 mm as a negative electrode material, one lithium plate, an aluminum plate, and the other lithium plate were placed in the negative electrode can in this order, and lithium and aluminum were mixed in the presence of an electrolyte. A non-aqueous electrolyte secondary battery having the same structure as Example 1 was produced except that the negative electrode was alloyed.

The batteries of Examples 1 to 4 and the battery of Comparative Example 1 were charged and discharged at 0.5 mAh at a constant current of 1.0 mA for 1.
0.5 when cycled in the voltage range of 5-2.5v
The relationship between the battery voltage at the end of mAh discharge and the number of charge/discharge cycles was investigated, and the results are shown in FIG.

As shown in Figure 5, the batteries of Examples 1 to 4 in which copper, nickel, gallium, copper, and bismuth were dispersed in aluminum without alloying were different from the battery of Comparative Example 1 in which only aluminum was used. Compared to 0, 5 in each cycle
The battery voltage at the end of mAh discharge was high, and the number of cycles capable of 0.5 mAh discharge was large when viewed at the end of 1.5 V, and the charge/discharge cycle characteristics were excellent.

Example 5 In place of the aluminum-copper structure in Example 1, an aluminum alloy-steel structure was used in which the aluminum part of the aluminum-copper structure shown in FIG. 3 was replaced with an aluminum alloy containing 4 atomic percent gallium. A non-aqueous electrolyte secondary battery having the same configuration as in Example 1 except for the use of the following materials was produced.

Comparative Example 2 The same as Example 5 except that an aluminum-gallium alloy plate having a thickness of 0.3 mm and a diameter of 7.8 mm and containing 4 at.% of gallium was used instead of the aluminum alloy-fIIl structure in Example 5. A non-aqueous electrolyte secondary battery having a similar configuration was fabricated.

Regarding the battery of Example 5 and the battery of Comparative Example 2, 1
．． 0.5mAh charging/discharging at QmA constant current 1.5~2
．． 0.5mA when cycled in a 5v voltage range
The relationship between the battery voltage at the end of h-discharge and the number of charge/discharge cycles was investigated, and the results are shown in FIG.

As shown in Figure 6, the battery of Example 5, in which copper was dispersed in the aluminum-gallium alloy, had a lower discharge rate of 0.5 mAh in each cycle than the battery of Comparative Example 2, which used only the aluminum-gallium alloy. The battery voltage at the end of the test was high and the charge/discharge cycle characteristics were excellent.

Example 6 The same as Example 1 except that instead of the aluminum-copper structure in Example 1, a bismuth-steel structure having the structure in which the aluminum cavity shown in FIG. 3 was replaced by replacing the aluminum part of the structure with bismuth was used. A non-aqueous electrolyte secondary battery with the same configuration was fabricated.

Example 7 In place of the aluminum-copper structure in Example 1, a bismuth-gallium-nickel structure ( Weight ratio of bismuth, gallium, and nickel: 70:20:10)
A non-aqueous electrolyte secondary battery having the same configuration as in Example 1 was manufactured except that the following was used.

Comparative Example 3 Instead of the bismuth-copper structure in Example 6, a thickness of 0
．． 3m++s, diameter? A non-aqueous electrolyte secondary battery having the same structure as in Example 6 was produced except that a bismuth plate of .hm was used.

Regarding the batteries of Examples 6 and 7 and the battery of Comparative Example 3, 1. Charge/discharge of 0.5mAh with constant current of QmA to 1.0
0.5 when cycled over a voltage range of ~1.6 V
The relationship between the battery voltage at the end of rrrA h 11t frost and the number of charge/discharge cycles was investigated, and the results are shown in FIG.

As shown in FIG. 7, the battery of Example 6 in which copper was dispersed in bismuth without being alloyed, and the battery in Example 7 in which gallium and nickel were dispersed in bismuth without being alloyed,
Compared to the battery of Comparative Example 3 using only bismuth, the battery voltage at the end of 0 and 5 mAh discharge in each cycle was high and the charge/discharge cycle characteristics were excellent.

Example 8 In place of the aluminum-copper structure in Example 1, a boron-antimony-copper structure (boron ,
A non-aqueous electrolyte secondary battery having the same structure as in Example 1 was produced except that the weight ratio of antimony and copper was 70:20:10.

Comparative Example 4 A non-aqueous electrolyte secondary battery having the same configuration as Example 8 was used, except that a boron plate with a thickness of 0.31 and a diameter of 7.8 a+m was used in place of the boron-antimony-copper structure in Example 9118. Created.

Regarding the battery of Example 8 and the battery of Comparative Example 4, 1
．． Charging and discharging 0.25mA h with a constant current of 0mA
．． 0.0 when cycled in the voltage range of 5-2.5V.
The relationship between the battery voltage at the end of 25 mAh discharge and the number of charge/discharge cycles was investigated, and the results are shown in FIG.

As shown in FIG. 8, the battery of Example 8 in which antimony and copper were dispersed in boron is different from the battery in Comparative Example 4 in which only boron was used.
0,25 mA in each cycle compared to a battery of
The battery voltage at the end of h discharge was high, and the number of 0.25 mA h discharge burnable cycles when viewed at the end of 1.5V was also large, and the charge/discharge cycle characteristics were excellent.

〔Effect of the invention〕

As explained above, in the present invention, an alkali metal is electrochemically alloyed with a metal structure formed by dispersing the opening IBM' without alloying it in the main metal M to be alloyed with the alkali metal. By configuring the negative electrode, it was possible to prevent the negative electrode from becoming finer or to collapse, and to improve charge/discharge cycle characteristics.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a non-aqueous electrolyte secondary battery according to the present invention, and FIG. 2 is a sectional view showing a state before the negative electrode material of the battery shown in FIG. 1 is alloyed. FIG. 3 is a partially enlarged sectional view schematically showing an example of a metal structure used in the non-aqueous electrolyte secondary battery of the present invention, and FIG. FIG. 3 is a partially enlarged cross-sectional view schematically showing another example of the metal structure. FIG. 5 is a diagram showing the relationship between the battery voltage at the end of 0.5 mAh discharge and the number of charge/discharge cycles when the batteries of Examples 1 to 4 and the battery of Comparative Example 1 are repeatedly charged and discharged. Figure 6 shows Example 5.
FIG. 3 is a graph showing the relationship between the battery voltage at the end of 0.5 mAh discharge and the number of charge/discharge cycles when the battery of Comparative Example 2 and the battery of Comparative Example 2 are repeatedly charged and discharged. FIG. 7 is a diagram showing the relationship between the battery voltage at the end of 0.5 mAh discharge and the number of charge/discharge cycles when the batteries of Examples 6 to 7 and the battery of Comparative Example 3 are repeatedly charged and discharged. Figure 8 shows the 0.0% difference when the battery of Example 8 and the battery of Comparative Example 4 were repeatedly charged and discharged.
It is a figure which shows the relationship between the battery voltage at the end of 25mAh discharge, and the number of charging/discharging cycles. 3... Negative electrode, 3a, 3c... Alkali metal plate, 3
b...Metal structure, 6...Positive electrode, 11...Aluminum, 12...Copper, 2)...Aluminum, 22...Gallium, 23...Copper dimension ω- Shinobu Figure 8 Number of charge/discharge cycles (times)

Claims (8)

[Claims] (1) In a nonaqueous electrolyte secondary battery comprising a positive electrode, an alkali metal ion conductive nonaqueous electrolyte, and a negative electrode, the negative electrode has a main metal M alloyed with the alkali metal and a submetal M'
A non-aqueous electrolyte secondary battery characterized in that it is constructed by electrochemically alloying an alkali metal with a metal structure formed by dispersing the metal without alloying it. (2) The non-aqueous electrolyte secondary battery according to claim 1, wherein the secondary metal M' is a metal that does not alloy with an alkali metal. (3) The non-aqueous electrolyte secondary battery according to claim 1, wherein the secondary metal M' is a metal that alloys with an alkali metal. (4) The nonaqueous electrolyte secondary battery according to claim 1, wherein the submetal M' comprises a metal that alloys with an alkali metal and a metal that does not alloy with an alkali metal. (5) The ratio of main metal M and sub metal M' is 1:1 by weight
~99:1 Claims 1, 2, and 3
4. The non-aqueous electrolyte secondary battery according to item 4. (6) The main metal M is at least one selected from aluminum, bismuth, antimony, arsenic, boron, gallium, indium, germanium or an alloy thereof, and the secondary metal M' is copper, titanium, iron, nickel, The nonaqueous electrolyte secondary battery according to claim 2, which is at least one selected from tantalum, zirconium, stainless steel, or an alloy thereof. (7) The main metal M is aluminum, and the secondary metal M' is copper, titanium, nickel, bismuth, antimony, arsenic, silicon,
The nonaqueous electrolyte secondary battery according to claim 1, which is at least one selected from boron, indium, gallium, and germanium. (8) Claims 1, 2, and 3, wherein the alkali metal is lithium and the positive electrode active material is titanium disulfide;
The nonaqueous electrolyte secondary battery according to item 4, 5, 6, or 7.