JP2005251516A - Nonaqueous electrolyte secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a nonaqueous electrolyte secondary battery for improving a charge/discharge cycle property. <P>SOLUTION: This battery includes an elemental sulfur as an active material and has a positive electrode 1 including at least a styrene-butadiene rubber as a binder; a negative electrode 2 including a material storing and discharging a lithium ion; and a nonaqueous electrolyte 5 with magnesium iodide to be metal halide added thereto. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte secondary battery, and more particularly to a non-aqueous electrolyte secondary battery provided with a non-aqueous electrolyte.

Conventionally, as a high energy density secondary battery, a nonaqueous electrolyte secondary battery that charges and discharges by moving lithium ions between a positive electrode and a negative electrode using a nonaqueous electrolyte is known. In this conventional nonaqueous electrolyte secondary battery, a lithium transition metal composite oxide such as LiCoO ₂ is used for the positive electrode, and a lithium metal, a lithium alloy, or a carbon material capable of inserting and extracting lithium ions is used for the negative electrode. . In addition, as the nonaqueous electrolytic solution, a nonaqueous electrolytic solution in which a solute (electrolyte salt) made of a lithium salt such as LiBF ₄ or LiPF ₆ is dissolved in an organic solvent such as ethylene carbonate or diethyl carbonate is used. In recent years, such conventional non-aqueous electrolyte secondary batteries have been used as power sources for various portable devices. Along with the increase in power consumption due to the multifunctional use of portable devices, a non-aqueous electrolyte secondary battery having a higher energy density is demanded.

However, in the conventional lithium secondary battery, the lithium transition metal composite oxide such as LiCoO ₂ used for the positive electrode has a large mass and a small number of reaction electrons, so that the capacity per unit mass (capacity density) is sufficient. However, there is a disadvantage that it is difficult to increase it.

Therefore, conventionally, in order to eliminate the above-described inconvenience, a technique of using a simple substance of sulfur having a high theoretical capacity density of about 1675 mAh / g as a positive electrode material has been proposed (for example, see Patent Document 1). In this conventional non-aqueous electrolyte secondary battery using sulfur as a positive electrode material, an ether-based material is used as an electrolyte.
JP-T-2001-520447

  However, in a conventional non-aqueous electrolyte secondary battery that uses sulfur alone as a positive electrode material, when an ether electrolyte is used, polysulfide is generated at the positive electrode by the reaction between sulfur and lithium during discharge. This polysulfide reacts with lithium in the negative electrode to cause self-discharge, and as a result, there is a problem that charge / discharge cycle characteristics are deteriorated.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a non-aqueous electrolyte secondary battery capable of improving charge / discharge cycle characteristics.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a non-aqueous electrolyte secondary battery according to a first aspect of the present invention includes a positive electrode containing sulfur alone as an active material and at least styrene-butadiene rubber as a binder, and occlusion and release of lithium ions. And a non-aqueous electrolyte to which a metal halide is added.

  In the non-aqueous electrolyte secondary battery according to the first aspect, as described above, by adding a metal halide to the non-aqueous electrolyte in the non-aqueous electrolyte secondary battery using the positive electrode containing sulfur alone as the active material. Since the metal halide reacts with the negative electrode to form a film on the surface of the negative electrode, it is possible to prevent the polysulfide produced by the reaction between sulfur and lithium at the positive electrode during discharge from reacting with the negative electrode. Thereby, since the self-discharge phenomenon resulting from the reaction between polysulfide and the negative electrode can be suppressed, the charge / discharge cycle characteristics of the non-aqueous electrolyte secondary battery can be improved. In addition, since the expansion | swelling of the electrode (positive electrode) by impregnation of a nonaqueous electrolyte can be suppressed by using the binder containing a styrene-butadiene rubber for a positive electrode, the charge / discharge cycle characteristic resulting from expansion | swelling of an electrode (positive electrode) Can be suppressed.

  In the nonaqueous electrolyte secondary battery according to the first aspect, preferably, the metal halide is a metal iodide. If comprised in this way, a metal iodide reacts with a negative electrode and forms a firm film on the surface of a negative electrode, Therefore The polysulfide produced | generated by sulfur and lithium reacting with a positive electrode at the time of discharge reacts with a negative electrode Can be effectively suppressed. Thereby, since the self-discharge phenomenon resulting from the reaction between polysulfide and the negative electrode can be effectively suppressed, the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery can be easily improved.

  In the non-aqueous electrolyte secondary battery including the non-aqueous electrolyte to which the metal iodide is added, preferably, the metal iodide is magnesium iodide. With this configuration, magnesium iodide reacts with the negative electrode to form a stronger film on the surface of the negative electrode, so that polysulfide generated by the reaction between sulfur and lithium at the positive electrode during discharge reacts with the negative electrode. Can be more effectively suppressed. Thereby, since the self-discharge phenomenon resulting from the reaction between polysulfide and the negative electrode can be more effectively suppressed, the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery can be improved more easily. This effect has been proved by a comparative experiment described later.

  In the non-aqueous electrolyte secondary battery including the non-aqueous electrolyte to which the metal iodide is added, preferably, the metal iodide is aluminum iodide. If comprised in this way, since aluminum iodide reacts with a negative electrode and forms a firmer film on the surface of a negative electrode, the polysulfide produced | generated when sulfur and lithium react with the positive electrode at the time of discharge will react with a negative electrode Can be more effectively suppressed. Thereby, since the self-discharge phenomenon resulting from the reaction between polysulfide and the negative electrode can be more effectively suppressed, the charge / discharge cycle characteristics of the nonaqueous electrolyte secondary battery can be improved more easily. This effect has been proved by a comparative experiment described later.

  In the non-aqueous electrolyte secondary battery according to the first aspect, preferably, the negative electrode includes one of a carbon material and a silicon material. If a negative electrode made of such a material is used, a strong film capable of easily preventing self-discharge can be formed on the surface of the negative electrode by adding a metal halide to the nonaqueous electrolyte. In addition, when a carbon material and a silicon material are used as the negative electrode, unlike the case where lithium is used for the negative electrode, dendritic (dendritic) precipitates are not generated on the negative electrode surface, which is preferable.

  Examples of the present invention will be specifically described below.

  In the present application, as examples corresponding to the present invention, lithium secondary batteries (nonaqueous electrolyte secondary batteries) according to the following Examples 1 and 2 are manufactured, and as Comparative Examples, the following Comparative Examples 1 to 1 are made. No. 4 lithium secondary batteries were prepared and the characteristics were compared.

(Common to Examples 1, 2 and Comparative Examples 1-4)
[Production of positive electrode]
Sulfur (60% by mass) as an active material, Ketjen black (35% by mass) as a conductive agent, polytetrafluoroethylene (3% by mass) as a binder (binder) and styrene-butadiene rubber (1 Mass%) and carboxymethyl cellulose (1 mass%) as a thickener were mixed, and water was added thereto to form a slurry. And this slurry was uniformly apply | coated to the single side | surface of the aluminum foil as a positive electrode collector by the doctor blade method. Thereafter, the slurry was dried at 50 ° C. under vacuum to evaporate the water, and positive electrodes of lithium secondary batteries according to Examples 1, 2 and Comparative Examples 1 to 4 were produced.

[Preparation of non-aqueous electrolyte]
(Comparative Example 1)
Lithium bis (trifluoromethylsulfone) imide LiN (CF ₃ SO ₂ ) ₂ is added to an electrolyte in which 1,3-dioxolane and dimethoxyethane are mixed at a volume ratio of 1: 9 so as to have a concentration of 0.5 mol / l. The nonaqueous electrolyte solution of the lithium secondary battery by the comparative example 1 was prepared by melt | dissolving in.

(Comparative Example 2)
In Comparative Example 2, by adding 0.1 M magnesium bis (trifluoromethanesulfone) imide Mg (TFSI) ₂ as an additive to the non-aqueous electrolyte according to Comparative Example 1 produced as described above, A nonaqueous electrolyte solution for a lithium secondary battery according to Comparative Example 2 was prepared.

(Comparative Example 3)
In Comparative Example 3, in the non-aqueous electrolyte according to Comparative Example 1 fabricated as described above, by adding 0.1M of iodine I ₂ as an additive, non-rechargeable lithium battery according to Comparative Example 3 A water electrolyte was prepared.

(Comparative Example 4)
In Comparative Example 4, a lithium secondary battery according to Comparative Example 4 was added to the nonaqueous electrolytic solution according to Comparative Example 1 produced as described above by adding 0.1 M lithium borofluoride LiBF ₄ as an additive. A non-aqueous electrolyte was prepared.

(Example 1)
In Example 1, a lithium secondary battery according to Example 1 was added by adding 0.1 M magnesium iodide MgI ₂ as an additive to the non-aqueous electrolyte according to Comparative Example 1 manufactured as described above. A non-aqueous electrolyte was prepared.

(Example 2)
In Example 2, the lithium secondary battery according to Example 2 was added to the nonaqueous electrolyte solution according to Comparative Example 1 manufactured as described above by adding 0.1 M aluminum iodide AlI ₃ as an additive. A non-aqueous electrolyte was prepared.

(Common to Examples 1, 2 and Comparative Examples 1-4)
[Production of test cell]
FIG. 1 is a perspective view showing a test cell produced for examining the characteristics of the positive electrode of the nonaqueous electrolyte secondary battery according to Example 1, Example 2, and Comparative Examples 1 to 4. FIG. Referring to FIG. 1, as a test cell manufacturing process, positive electrode 1 and negative electrode 2 were arranged in test cell container 10 such that positive electrode 1 and negative electrode 2 face each other with separator 3 interposed therebetween. The reference electrode 4 was also disposed in the test cell container 10. And the test cell was produced by inject | pouring the non-aqueous electrolyte 5 in the test cell container 10. FIG. In addition, as the positive electrode 1, while using the positive electrode by Example 1, Example 2 and Comparative Examples 1-4 which were produced as mentioned above, as the negative electrode 2 and the reference electrode 3, the lithium metal was used. Moreover, as the non-aqueous electrolyte 5, the non-aqueous electrolytes according to Examples 1 and 2 and Comparative Examples 1 to 4 manufactured as described above were used.

[Charge / discharge test]
A charge / discharge test was performed on each test cell corresponding to Example 1, Example 2, and Comparative Examples 1 to 4 manufactured as described above. The charge and discharge conditions, the discharge current of 0.5 mA / cm ^2, after discharged up to discharge cutoff potential of 1.5V (vs.Li/Li ^+), charging current of 0.5 mA / cm ^2, The battery was charged to a charge end potential of 2.8 V (vs. Li ^/ Li ⁺ ). And this charging / discharging was made into 1 cycle, and charging / discharging was performed to 10th cycle. The results are shown in Table 1, FIG. 2 and FIG.

  Specifically, FIG. 2 and FIG. 3 show charge / discharge cycle characteristics up to the 10th cycle of charge / discharge performed for the test cells of Example 1 and Example 2, respectively. Table 1 shows the charge / discharge characteristics of the test cells corresponding to Comparative Examples 1 to 4, Example 1 and Example 2, respectively. In addition, the capacity density in Table 1 and the capacity maintenance rate after 10 cycles are respectively obtained by the following equations.

Capacity density (mAh / g) = Current flowed (mAh) / (Total mass of active material, conductive agent, binder and thickener) (g)
Capacity maintenance ratio after 10 cycles (%) = (discharge capacity density at 10th cycle (mAh / g) / initial discharge capacity density (mAh / g)) × 100 (%)
Referring to Table 1, in Comparative Example 1 in which no additive was added to the nonaqueous electrolytic solution, the initial discharge capacity density was 724 mAh / g, and the capacity retention rate after 10 cycles was 69%. . In Comparative Example 2 in which 0.1 M magnesium bis (trifluoromethanesulfone) imide Mg (TFSI) ₂ was added as an additive, the initial discharge capacity density was 722 mAh / g, which was lower than that in Comparative Example 1, and 10 cycles. The subsequent capacity retention rate was 63%, which was lower than that of Comparative Example 1. Further, in Comparative Example 3 in which 0.1 M iodine I ₂ was added as an additive, the initial discharge capacity density was 345 mAh / g lower than that in Comparative Example 1, and the capacity retention rate after 10 cycles was Comparative Example 1. It was 56% lower. Further, in Comparative Example 4 in which 0.1 M lithium borofluoride LiBF ₄ was added as an additive, the initial discharge capacity density was 624 mAh / g lower than that in Comparative Example 1, and the capacity retention rate after 10 cycles was compared. It was 45% lower than Example 1. Thus, in Comparative Examples 2 to 4, the capacity retention rate (63%, 56%, 45%) is lower than the capacity retention rate (69%) of Comparative Example 1 in which no additive was added to the non-aqueous electrolyte. ) Turned out to be.

In contrast, as shown in Table 1, FIG. 1 and FIG. 2, Example 1 in which 0.1M magnesium iodide MgI ₂ was added as an additive and 0.1M aluminum iodide AlI ₃ as an additive was added. In the added Example 2, it was found that a higher capacity retention ratio (76%, 71%) was obtained compared to the capacity retention ratio (69%) of Comparative Example 1 in which no additive was added to the non-aqueous electrolyte. did.

Further, the capacity retention rate (76%) of Example 1 in which magnesium iodide MgI ₂ was added to the non-aqueous electrolyte was equal to the capacity retention rate (71 of Example 2 in which aluminum iodide AlI ₃ was added to the non-aqueous electrolyte solution. %). Thus, it is thought that it is based on the following reasons that Example 1 and Example 2 can obtain a high capacity | capacitance maintenance factor. That is, in Example 1 and Example 2, by adding magnesium iodide MgI ₂ and aluminum iodide AlI ₃ which are metal halides to the non-aqueous electrolyte, respectively, magnesium iodide MgI ₂ and aluminum iodide AlI ₃ Reacts with the lithium metal of the negative electrode to form an effective amount of a coating on the surface of the negative electrode. This coating suppresses the reaction of polysulfide produced by the reaction of sulfur and lithium at the positive electrode during discharge, so that the self-discharge phenomenon caused by the reaction between polysulfide and the negative electrode It is thought that it can be suppressed. As a result, it is considered that the charge / discharge cycle characteristics (capacity maintenance ratio) could be improved.

  In addition, it should be thought that the Example disclosed this time is an illustration and restrictive at no points. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above embodiment, magnesium iodide and aluminum iodide are used as the metal halide to be added to the non-aqueous electrolyte. However, the present invention is not limited to this, and lithium chloride, magnesium chloride, calcium chloride, aluminum chloride, Tin chloride, manganese chloride, iron chloride, cobalt chloride, nickel chloride, lithium bromide, magnesium bromide, calcium bromide, aluminum bromide, tin bromide, manganese bromide, iron bromide, cobalt bromide, nickel bromide At least one metal halide selected from the group consisting of lithium iodide, magnesium iodide, calcium iodide, aluminum iodide, tin iodide, manganese iodide, iron iodide, cobalt iodide and nickel iodide It may be used.

  Further, in the above examples, polytetrafluoroethylene and styrene-butadiene rubber were used as the binder to be added to the positive electrode. However, the present invention is not limited thereto, and polytetrafluoroethylene, polyvinylidene fluoride, polyethylene oxide, Similar effects can be obtained when at least one material selected from the group consisting of polyvinyl acetate, polymethacrylate, polyacrylate, polyacrylonitrile, polyvinyl alcohol, styrene-butadiene rubber and carboxymethylcellulose is used. However, when styrene-butadiene rubber is used, it is possible to obtain the effect of suppressing deterioration in charge / discharge cycle characteristics due to expansion of the positive electrode due to impregnation with the nonaqueous electrolyte, so that the binder containing styrene-butadiene rubber can be obtained. Is preferably used.

  Further, in the above examples, 4% by mass of a binder obtained by mixing polytetrafluoroethylene and styrene-butadiene rubber at a ratio of 3% by mass and 1% by mass, respectively, was added to the positive electrode. However, the present invention is not limited to this. The ratio of the binder added to the positive electrode may be 0.1% by mass or more and 50% by mass or less. In addition, the ratio of the binder is more preferably 0.1% by mass or more and 30% by mass or less, and further preferably 0.1% by mass or more and 20% by mass or less.

In the above embodiment, the electrolyte, and lithium bis (trifluoromethyl) imide _LiN (CF 3 _{SO 2) 2} solvent, the 1,3-dioxolane and dimethoxyethane 1: mixed at a volume ratio of 9 However, the present invention is not limited to this, and at least one solvent selected from cyclic ethers or chain ethers, and a room temperature molten salt having a melting point of 60 ° C. or lower. You may use the electrolyte solution which mixed. As described above, the reason why the ethers are mixed with the room temperature molten salt is that the room temperature molten salt has a large viscosity, so that only the room temperature molten salt makes it difficult for the electrolytic solution to be contained in the electrode. By mixing an appropriate amount of ethers with the room temperature molten salt, the electrolytic solution can easily be contained in the electrode, so that a reduction in discharge capacity density can be suppressed. However, if the ratio of the ethers to the room temperature molten salt is too large, it becomes close to the characteristics of an electrolytic solution consisting only of ethers, so that charge / discharge cycle characteristics deteriorate when charging and discharging sulfur alone. Therefore, the ratio of the ethers to the room temperature molten salt is preferably 40% or less by volume ratio. More specifically, the mixing ratio of the ethers and the room temperature molten salt is preferably set in the range of the volume ratio of 0.1: 99.9 to 40:60. Moreover, it is more preferable that the mixing ratio of the ethers and the room temperature molten salt is set in the range of the volume ratio of 0.1: 99.9 to 30:70. Moreover, it is more preferable that the mixing ratio of the ethers and the room temperature molten salt is set in the range of the volume ratio of 1:99 to 25:75. Moreover, it is most preferable to set the mixing ratio of ethers and room temperature molten salt (for example, quaternary ammonium salt) to a volume ratio of 10:90.

Moreover, as normal temperature molten salt, it is preferable that it is a liquid in a wide temperature range, for example, -20 degreeC-60 degreeC, and electrical conductivity is 10 ^<-4 > S / cm or more. In addition, since a normal temperature molten salt having a melting point of 60 ° C. or less has no vapor pressure and is flame retardant, the flammability of the electrolytic solution can be reduced as compared with the case where only ethers are used as the electrolytic solution.

The room temperature molten salt is preferably a quaternary ammonium salt. Examples of the quaternary ammonium salt include trimethylpropylammonium bis (trifluoromethylsulfonyl) imide ((CH ₃ ) ₃ N ⁺ (C ₃ H ₇ ) N ^— (SO ₂ CF ₃ ) ₂ ), trimethyloctylammonium. bis (trifluoromethylsulfonyl) imide ^{_{((CH 3) 3 N +}} (C 8 H 17) N - (SO 2 CF 3) 2), trimethyl allyl ammonium bis (trifluoromethylsulfonyl) imide ((CH _{3 ^{) 3 N + (Allyl) N}} - (SO 2 CF 3) 2), trimethyl hexyl ammonium bis (trifluoromethylsulfonyl) imide ^{_{((CH 3) 3 N +}} (C 6 H 13) N - (SO 2 CF _{3) 2),} trimethylethyl ammonium 2,2,2 N- (trifluoromethylsulfonyl) acetamide ^{_{((CH 3) 3 N +}} (C 2 H 5) (CF 3 CO) N - (SO 2 CF 3)), trimethyl allyl ammonium 2,2,2 -N- (trifluoromethylsulfonyl) acetamide ^{_{((CH 3) 3 N +}} (Allyl) (CF 3 CO) N - (SO 2 CF 3)), trimethylpropylammonium-2,2,2 -N - (trifluoromethylsulfonyl) acetamide ^{_{((CH 3) 3 N +}} (C 3 H 7) (CF 3 CO) N - (SO 2 CF 3)), tetraethylammonium 2,2,2-trifluoro -N - (trifluoromethylsulfonyl) acetamide ^{_{((C 2 H 5) 4}} N + (CF 3 CO) N - (SO 2 CF 3) And triethyl methyl ammonium 2,2,2-trifluoro -N- (trifluoromethylsulfonyl) acetamide ^{_{((C 2 H 5) 3}} N + (CH 3) (CF 3 CO) N - (SO 2 CF 3) ) And the like.

Examples of the cyclic ethers include 1,3-dioxolane, 4-methyl-1,3-dioxolane, tetrahydrofuran, 2-methyltetrahydrofuran, propylene oxide, 1,2-butylene oxide, 1,4-dioxane, 1, 3,5-trioxane, furan, 2-methylfuran, 1,8-cineol, crown ether and the like can be mentioned. Examples of the chain ethers include 1,2-dimethoxyethane, diethyl ether, dipropyl ether, diisopropyl ether, dibutyl ether, dihexyl ether, ethyl vinyl ether, butyl vinyl ether, methyl phenyl ether, ethyl phenyl ether, butyl phenyl ether, Pentylphenyl ether, methoxytoluene, benzylethyl ether, diphenyl ether, dibenzyl ether, ₀ -dimethoxybenzene, 1,2-diethoxyethane, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, 1 , 1-dimethoxymethane, 1,1-diethoxyethane, triethylene glycol dimethyl ether Etc. and tetraethylene glycol dimethyl ether.

  In the above embodiment, ketjen black is used as the conductive agent to be added to the positive electrode. However, the present invention is not limited to this, and a conductive carbon material other than ketjen black is added to the positive electrode. It may be used. In this case, the ratio of the conductive agent added to the positive electrode may be 5% by mass or more and 84% by mass or less. The proportion of the conductive agent is more preferably 5% by mass or more and 54% by mass or less, and further preferably 5% by mass or more and 20% by mass or less.

In the above embodiment, a non-aqueous electrolyte in which lithium bis (trifluoromethylsulfone) imide LiN (CF ₃ SO ₂ ) ₂ as a solute (lithium salt) is dissolved is used. However, the present invention is not limited to this. Alternatively, a nonaqueous electrolyte in which a lithium salt other than LiN (CF ₃ SO ₂ ) ₂ is dissolved may be used. Examples of lithium salts other than LiN (CF ₃ SO ₂ ) ₂ include LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , LiN (C ₂ F ₅ SO ₂ ) ₂ , LiAsF ₆ and difluoro. (Oxalato) lithium borate (substance represented by the chemical formula of the following chemical formula 1) and the like. Moreover, you may use the mixture which combined 2 or more selected from the group which consists of an above-described lithium salt.

  Moreover, in the said Example, although lithium metal was used as a negative electrode, this invention is not restricted to this, If lithium ion can be occluded and discharge | released, materials other than lithium metal will be used as a negative electrode active material. Also good. Examples of materials that can be used as the negative electrode active material include lithium materials, carbon materials such as graphite, and silicon. Here, since silicon (Si) has a high capacity, a high energy density non-aqueous electrolyte secondary battery can be obtained by using a negative electrode containing a negative electrode active material made of silicon. In addition, it is preferable to use a carbon material such as graphite and silicon as the negative electrode because dendritic (dendritic) precipitates are not generated on the surface of the negative electrode, unlike when lithium is used for the negative electrode.

It is the perspective view which showed the test cell produced in order to investigate the characteristic of the positive electrode of the nonaqueous electrolyte secondary battery by Example 1, Example 2, and Comparative Examples 1-4. 3 is a graph showing the results of a charge / discharge test performed on a test cell corresponding to Example 1. FIG. 6 is a graph showing the results of a charge / discharge test performed on a test cell corresponding to Example 2. FIG.

Explanation of symbols

1 Positive electrode 2 Negative electrode 5 Nonaqueous electrolyte

Claims (5)

A positive electrode containing sulfur alone as an active material and at least styrene-butadiene rubber as a binder;
A negative electrode comprising a material that occludes and releases lithium ions;
A non-aqueous electrolyte secondary battery comprising a non-aqueous electrolyte to which a metal halide is added.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the metal halide is a metal iodide.   The non-aqueous electrolyte secondary battery according to claim 2, wherein the metal iodide is magnesium iodide.   The non-aqueous electrolyte secondary battery according to claim 2, wherein the metal iodide is aluminum iodide.   The non-aqueous electrolyte secondary battery according to claim 1, wherein the negative electrode includes any one of a carbon material and a silicon material.

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