JP5870610B2 - Non-aqueous electrolyte iodine battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte iodine battery.

  Conventionally, a battery in which an activated carbon positive electrode and a lithium metal negative electrode are immersed in an organic non-aqueous polar solvent has been proposed in which halogen is added to an organic non-aqueous polar solvent (see Patent Document 1). By adding halogen in this way, it is said that there is no high voltage portion with a terminal voltage of 3.8 V or more, and the discharge voltage can be made flat. In addition, a battery in which a carbon positive electrode and a negative electrode made of lithium metal are arranged via a nonaqueous electrolytic solution containing lithium ions and halogen has been proposed (see Patent Document 2). With this battery, it is said that a high-capacity and high-output energy storage device can be realized.

Japanese Unexamined Patent Publication No. 63-168773 JP 2009-64584 A

  By the way, in the battery of patent document 1 and 2 mentioned above, lithium ion elutes from a metal lithium negative electrode at the time of discharge, and a halogen turns into a halogen ion in a positive electrode, and it is thought that the reverse reaction arises at the time of charge. Specifically, for example, when the halogen is iodine, it is considered that the reaction represented by the reaction formula (1) occurs at the negative electrode and the reaction formula (2) occurs at the positive electrode during charging and discharging. Since the standard electrode potential of lithium is −3.04 V and the standard electrode potential of iodine is +0.53 V, in such a battery, the theoretical maximum value of the operating voltage is 3.57 V. However, the operating voltage may not be sufficient with the theoretical voltage, and it has been desired to further increase the operating voltage.

  This invention is made | formed in view of such a subject, and it aims at providing the nonaqueous electrolyte iodine battery which can raise an operating voltage more.

  As a result of diligent research to achieve the above-mentioned object, the present inventors have found that when a predetermined compound having a lone electron pair is mixed with the positive electrode, the operating voltage can be further increased, and the present invention is completed. It came.

  That is, the non-aqueous electrolyte iodine battery of the present invention includes at least one compound containing at least one of sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus bonded to oxygen having a lone electron pair. And a non-aqueous ion conductive medium in which iodine is dissolved and interposed between the positive electrode and the negative electrode.

  The nonaqueous electrolyte iodine battery of the present invention can further increase the operating voltage. The reason why such an effect is obtained is not clear, but is presumed as follows. For example, it is thought that iodine dissolved in the ion conductive medium forms a molecular complex with a lone electron pair of a specific element (sulfur, phosphorus, etc.) present in a compound present in the positive electrode, thereby increasing the potential at which the positive electrode reaction occurs. It is done.

It is explanatory drawing which shows typically an example of the nonaqueous electrolyte iodine battery 10 of this invention. 2 is an explanatory diagram showing an outline of a configuration of a beaker cell 20. FIG. 2 is a discharge curve of Examples 1 and 2 and Comparative Example 1. 3 is a discharge curve of Example 3 and Comparative Example 2. It is a discharge curve of Example 4 and Comparative Example 3. It is a discharge curve of Examples 5-7. It is a discharge curve of Example 8 and Comparative Example 3.

  The nonaqueous electrolyte iodine battery of the present invention includes at least one compound containing any one or more of sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus bonded to oxygen having a lone electron pair. A positive electrode, a negative electrode, and a non-aqueous ion conductive medium in which iodine is dissolved between the positive electrode and the negative electrode.

  In the non-aqueous electrolyte iodine battery of the present invention, the positive electrode contains at least one or more of any one of sulfur having a lone pair, phosphorus having a lone pair, and phosphorus bonded to oxygen having a lone pair. A compound (hereinafter also referred to simply as a compound). The compound preferably contains one or more of sulfur having a lone electron pair and phosphorus having a lone electron pair, and more preferably contains sulfur having a lone electron pair. This is because discharging can be performed at a higher voltage. Moreover, this compound is good also as what forms a molecular complex with the iodine dissolved in the ion conduction medium, for example. Here, the molecular complex refers to a compound formed by directly bonding the same kind or two or more kinds of stable molecules at a certain ratio, and can also be referred to as a molecular compound. Whether or not to form a molecular complex with iodine can be determined by whether or not the peak due to the expansion and contraction of a predetermined bond in the Raman spectrum moves when iodine is added.

  This compound is preferably hardly soluble in the ion conductive medium, and more preferably insoluble. If it carries out like this, in the case of charging / discharging, it will be easy to exchange electrons in a positive electrode between iodine. This compound includes sulfur, a sulfur compound to which a cyclic compound is bonded and a polymer thereof, a heterocyclic compound and a polymer containing sulfur, a phosphorus compound to which a cyclic compound is bonded, a cyclic compound and a phosphorus compound to which oxygen is bonded. Can be mentioned. Examples thereof include sulfur, polycyclic thiophene compounds, phenylphosphine compounds, phenylphosphine sulfide compounds, phenylene sulfide polymers, thiophene polymers, carbon sulfide polymers, and phosphine oxide compounds. Examples of the polycyclic thiophene compound include a cyclic thiophene derivative (cyclic tetrathiophene, chemical formula 1), a polycyclic thiophene compound (monkey flower, chemical formula 2), and the like. Examples of the phenylphosphine compound include triphenylphosphine (Chemical Formula 3). Examples of the phenylphosphine sulfide compound include triphenylphosphine sulfide (Chemical Formula 4). Examples of the phenylene sulfide-based polymer include polyparaphenylene sulfide (Chemical Formula 5). Examples of the thiophene-based polymer include poly (3-hexylthiophene) (Chemical Formula 6). A carbon sulfide polymer (Chemical Formula 7) is also included. Examples of the phosphine oxide compound include triphenylphosphine oxide (Chemical Formula 8). Among these, sulfur, a polycyclic thiophene compound, a phenylene sulfide-based polymer, a thiophene-based polymer, a carbon sulfide polymer, and the like are preferable, and a polymer-based compound containing sulfur is more preferable because of ease of handling.

  In the nonaqueous electrolyte iodine battery of the present invention, the positive electrode uses iodine as a positive electrode active material. This positive electrode active material is supplied by iodine dissolved in an ion conductive medium. For example, the positive electrode may be formed by mixing a compound, a conductive material, and a binder to form a positive electrode mixture on the surface of the current collector, and compressing to increase the electrode density as necessary. Good. As a method for mixing the positive electrode mixture, an appropriate solvent may be added and wet mixed with the conductive material and the binder. Moreover, you may dry-mix using a mortar etc. As the solvent, for example, a known solvent such as N-methylpyrrolidone can be used. The mixing amount of the compound is not particularly limited, but is preferably 30% by mass or more and 80% by mass or less with respect to the whole positive electrode mixture. When the mixing amount of the compound is 30% by mass or more, the operating voltage can be further increased, and when it is 80% by mass or less, the amount of the conductive material and the binder is relatively increased, and the conductivity and mechanical strength are further increased. be able to. Moreover, a binder should just be 3 mass% or more and 20 mass% or less with respect to the whole positive electrode compound material, for example. The conductive material is not particularly limited as long as it is an electron conductive material that does not adversely affect the performance of the battery. For example, graphite such as natural graphite (scale-like graphite, scale-like graphite) or artificial graphite, acetylene black, carbon black, kettle, etc. A mixture of one or more of chain black, carbon whisker, needle coke, carbon fiber, activated carbon, metal (copper, nickel, aluminum, silver, gold, etc.) can be used. Among these, as the conductive material, carbon black and acetylene black are preferable from the viewpoints of electron conductivity and coatability. The binder plays a role of fastening the positive electrode mixture, for example, a fluorine-containing resin such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine rubber, or heat such as polypropylene or polyethylene. A plastic resin, ethylene-propylene-dienemer (EPDM), sulfonated EPDM, natural butyl rubber (NBR) or the like can be used alone or as a mixture of two or more. In addition, an aqueous dispersion of cellulose or styrene butadiene rubber (SBR), which is an aqueous binder, can also be used. Current collectors include aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, and aluminum, copper, etc. for the purpose of improving adhesion, conductivity, and oxidation resistance. A surface treated with carbon, nickel, titanium, silver or the like can be used. For these, the surface can be oxidized. Examples of the shape of the current collector include foil, film, sheet, net, punched or expanded, lath, porous, foam, and formed fiber group. The thickness of the current collector is, for example, 1 to 500 μm.

For the negative electrode of the nonaqueous electrolyte iodine battery of the present invention, for example, a material that releases lithium ions may be used as the negative electrode active material. Examples of the negative electrode active material include, in addition to metallic lithium and lithium alloys, carbonaceous materials that occlude and release lithium ions. Examples of the lithium alloy include alloys of lithium with aluminum, silicon, tin, magnesium, indium, calcium, and the like. Examples of the carbonaceous material that releases lithium ions include graphite, coke, mesophase pitch carbon fiber, spherical carbon, and resin-fired carbon. This negative electrode is prepared by, for example, mixing a negative electrode active material, a binder and, if necessary, a conductive material, adding a suitable solvent to form a paste-like negative electrode material, and applying and drying it on the surface of the current collector. If necessary, it may be compressed to increase the electrode density. As the conductive material and the binder, those mentioned for the positive electrode can be used. In addition to copper, nickel, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, etc., the negative electrode current collector can be made of, for example, copper or the like for the purpose of improving adhesion, conductivity, and reduction resistance. Those whose surfaces are treated with carbon, nickel, titanium, silver, or the like can also be used. For these, the surface can be oxidized. The shape of the current collector may be the same as that of the positive electrode. Note that a known coating such as a reaction coating with vinylene carbonate, fluoroethylene carbonate, chloroethylene carbonate, CO ₂ , HF, HI, AlI _3, MgI ₂ or the like may be provided on the surface of the negative electrode.

  In the non-aqueous electrolyte iodine battery of the present invention, the ion conductive medium may be interposed between the positive electrode and the negative electrode to dissolve iodine. Moreover, it is good also as what contains an alkali metal ion (for example, lithium ion) and conducts this alkali metal ion. This ion conductive medium may be a non-aqueous electrolyte solution in which iodine and a supporting salt are dissolved. Non-aqueous electrolytes include, for example, ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (γ-BL), diethyl carbonate (DEC), dimethyl carbonate (DMC), dioxane, hexaethoxycyclotriphosphazene. Organic solvents used for conventional secondary batteries and capacitors, such as 3-methoxypropionitrile, or mixed solvents thereof may be included. Dioxane, trimethyl phosphate, triethyl phosphate, tributyl phosphate, dimethyl sulfoxide, sulfolane and the like can also be used. The ion conductive medium may be a non-aqueous electrolyte solution gelled with a known gelling agent. Examples thereof include gel electrolytes in which an electrolyte containing a supporting salt is contained in a saccharide such as a polymer such as polyvinylidene fluoride, polyethylene glycol, or polyacrylonitrile, an amino acid derivative, or a sorbitol derivative. In this ionic conduction medium, the concentration of iodine is not particularly limited, but is preferably not more than a saturated concentration (maximum non-aqueous electrolyte solution and iodine up to 1: 1 in molar ratio), 1.0 mol / L or less. Is more preferable. This is because, if the concentration is lower than the saturation concentration, iodine is dissolved in the ion conductive medium, so that it is considered difficult to inhibit lithium ion conduction. At this time, the iodine concentration is preferably 0.05 mol / L or more and 0.80 mol / L or less.

In the ion conductive medium of the present invention, the supporting salt is not particularly limited. For example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF _{3 SO 2) 3, LiSbF 6,} LiSiF 6, LiAlF 4, LiSCN, LiClO 4, LiCl, LiF, LiBr, LiI, and the like LiAlCl _4. Among these, from the group consisting of inorganic salts such as LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , and organic salts such as LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiC (CF ₃ SO ₂ ) _3. It is preferable from the viewpoint of electrical characteristics to use a combination of one or two or more selected salts. An ion conductive medium containing such a supporting salt will contain lithium ions. The concentration of the supporting salt is preferably 0.1 mol / L or more and 2.0 mol / L or less, and more preferably 0.8 mol / L or more and 1.2 mol / L or less.

  The nonaqueous electrolyte iodine battery of the present invention may include a separator between the negative electrode and the positive electrode. The separator is not particularly limited as long as it has a composition that can withstand the range of use of the nonaqueous electrolyte iodine battery. For example, a polymer nonwoven fabric such as a polypropylene nonwoven fabric or a polyphenylene sulfide nonwoven fabric, or a fine olefin resin such as polyethylene or polypropylene is used. A porous film is mentioned. These may be used alone or in combination.

  The shape of the nonaqueous electrolyte iodine battery of the present invention is not particularly limited, and examples thereof include a coin type, a button type, a sheet type, a laminated type, a cylindrical type, a flat type, and a square type. Moreover, you may apply to the large sized thing etc. which are used for an electric vehicle etc. FIG. 1 is an explanatory view schematically showing an example of the nonaqueous electrolyte iodine battery 10 of the present invention. In this nonaqueous electrolyte iodine battery 10, a negative electrode 12 and a positive electrode 13 made of a lithium metal foil are arranged to face each other with an ion conductive medium 18 therebetween. Among these, the positive electrode 13 is produced by mixing the compound 14, the conductive material 15, and the binder 16 and then press-molding the current collector 17 such as a platinum mesh. In addition, the positive electrode 13 includes, as the compound 14, a compound containing one or more of sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus bonded to oxygen having a lone electron pair. This compound 14 is a compound that forms a molecular complex with iodine.

  The nonaqueous electrolyte iodine battery of the present invention described in detail above contains at least one or more of any one of sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus bonded to oxygen having a lone electron pair. This compound is contained in the positive electrode, and the operating voltage can be further increased. In addition, the nonaqueous electrolyte iodine battery of the present invention not only increases the initial operating voltage due to electrical interaction by forming a molecular complex with a compound having an element having a lone electron pair. It is considered that a high potential can be maintained during discharge.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  Below, the example which produced the nonaqueous electrolyte iodine battery of this invention concretely is demonstrated as an Example.

[Example 1]
The positive electrode was produced as follows. 35 mg of ketjen black (ECP-6000 manufactured by Mitsubishi Chemical) as a conductive material, 15 mg of polytetrafluoroethylene (manufactured by Daikin Industries) as a binder, and 50 mg of sulfur as a compound of the present invention in a dry mortar And kneaded to obtain a sheet-like positive electrode mixture. The positive electrode mixture (weight 3 mg, area 0.29 cm ² ) was pressure-bonded to a Pt mesh (manufactured by Niraco) to obtain a positive electrode. For the negative electrode, metal lithium (made by Honjo Metal) having a thickness of 0.4 mm was used. As the electrolytic solution, 190 mg of iodine was dissolved in 12 mL of a 1 mol / L lithium bis (trifluoromethanesulfonylimide) propylene carbonate solution (Toyama Pharmaceutical Co., Ltd.). Using this positive electrode, negative electrode, and electrolytic solution, an evaluation cell was prepared as follows. FIG. 2 is an explanatory diagram showing an outline of the configuration of the beaker cell 20. As shown in FIG. 2, the positive electrode 22 and the negative electrode 24 were set in a glass beaker 21 in a glove box under an argon atmosphere, and an electrolyte solution 26 was injected. Next, a plastic lid 28 was attached to the open portion of the beaker 21 to form a beaker cell 20 (F-type cell) as an evaluation cell. The space in the beaker cell 20 is filled with argon. The capacity of the beaker cell 20 is about 30 ml. The evaluation cell thus obtained was named Example 1.

[Comparative Example 1]
A cell obtained through the same process as Example 1 was used as Comparative Example 1 except that the compound of the present invention was not added as the positive electrode mixture. The positive electrode mixture was obtained by kneading 190 mg of ketjen black and 35 mg of polytetrafluoroethylene in a dry manner using a mortar.

[Example 2]
A cell obtained through the same steps as in Example 1 except that a cyclic thiophene derivative (compound of Formula 1: Compound 1) was mixed instead of sulfur in Example 1 was defined as Example 2. Compound 1 was synthesized as follows. Using 3,4-dibromothiophene as a starting material, a dimer was prepared first, and the dimer was reacted to synthesize Compound 1 as a tetramer. The synthesis of the dimer was carried out by using 3,4-dibromothiophene (Wako Pure Chemicals) 12.9 mL in tetrahydrofuran (THF) solution (11.8 mL) in THF solution of isopropylmagnesium chloride-lithium chloride complex (1.3 M, 100 mL, Aldrich) was added dropwise at 0 ° C. After stirring this for 1 hour, it stirred at room temperature for 30 minutes. This was again cooled to 0 ° C. and then added dropwise to a THF solution (10 mL) of cupric chloride (23.7 g). Then, it heated up gradually to room temperature and stirred overnight. After adding a 5N aqueous hydrochloric acid solution, the organic layer was separated, and the aqueous layer was extracted with diethyl ether. The organic layers were combined, washed with saturated brine, dried over sodium sulfate and filtered, and then the solvent was distilled off under reduced pressure. The reaction mixture was purified by silica gel column chromatography and further recrystallized from hexane to obtain a dimer. Next, a tetramer was synthesized. To a dimethylformamide solution (40 mL) of 1,5-cyclooctadiene (3.50 mL) and 2,2′-bipyridyl (4.08 g), 7.18 g of Ni (COD) ₂ was added at room temperature. A dimer (7.69 g) in THF (40 mL) was added dropwise thereto, and the mixture was heated at 70 ° C. for 24 hours. After adding 5N hydrochloric acid, the organic layer was separated and the aqueous layer was extracted with chloroform. The organic layers were combined and washed with saturated brine, dried over sodium sulfate, filtered, and then the solvent was distilled off under reduced pressure. The reaction mixture was purified by silica gel column chromatography, and further recrystallized from hexane to obtain a tetramer.

(Battery performance evaluation)
The obtained cells of Examples 1 and 2 and Comparative Example 1 were connected to a charge / discharge device (HJ1001SM8A) manufactured by Hokuto Denko, and discharged by flowing a current of 0.02 mA between the positive electrode and the negative electrode. FIG. 3 is a discharge curve of Examples 1 and 2 and Comparative Example 1. In Example 1, the open circuit voltage was 3.81 V, and the operating voltage at the time of discharge amount 0.3 mAh was 3.59 V. In Example 2, the open circuit voltage was 3.80V and the operating voltage was 3.62V. In Comparative Example 1, the open circuit voltage was 3.58V and the operating voltage was 3.51V. In addition, the discharge characteristic was measured similarly to Example 1 also in the Example and comparative example which are mentioned later.

[Example 3]
A cell obtained in Example 3 was obtained through the same steps as in Example 1 except that trimethyl phosphate was used instead of propylene carbonate. FIG. 4 is a discharge curve of Example 3 and Comparative Example 2. In Example 3, the open circuit voltage was 4.10 V, and the operating voltage at the discharge amount of 0.3 mAh was 4.015 V.

[Comparative Example 2]
A cell obtained in Comparative Example 2 was obtained through the same process as Comparative Example 1 except that trimethyl phosphate was used instead of propylene carbonate. In Comparative Example 2, the open circuit voltage was 4.08V and the operating voltage was 3.991V.

[Example 4]
The positive electrode was obtained as follows. Ketjen black 126 mg, polytetrafluoroethylene 51 mg, polyparaphenylene sulfide (compound of chemical formula 5) 226 mg were kneaded dry using a mortar to obtain a sheet-like positive electrode mixture. The positive electrode mixture (weight 3 mg, area 0.29 cm ² ) was pressure bonded to a Pt mesh to obtain a positive electrode member. Metal lithium having a thickness of 0.4 mm was used for the negative electrode. In the beaker cell shown in FIG. 2, a positive electrode and a negative electrode were set in a glove box under an argon atmosphere. As the electrolytic solution, a solution in which 220 mg of iodine was dissolved in 12 mL of an ethylene carbonate / diethyl carbonate solution of 1 mol / L lithium perchlorate (mixing ratio 3: 7, Toyama Pharmaceutical) was used. FIG. 5 shows discharge curves of Example 4 and Comparative Example 3. In Example 4, the open circuit voltage was 3.80 V, and the operating voltage at the time of discharge amount 1.0 mAh was 3.54 V.

[Comparative Example 3]
The cell of Comparative Example 3 was obtained through the same steps as in Example 4 except that 190 mg of ketjen black and 35 mg of polytetrafluoroethylene were kneaded in a dry mortar and used as the positive electrode mixture. In Comparative Example 3, the open circuit voltage was 3.53V and the operating voltage was 2.91V.

[Example 5]
90 mg of ketjen black, 40 mg of polytetrafluoroethylene, and 210 mg of triphenylphosphine (chemical formula 3 compound, manufactured by Aldrich) were kneaded dry using a mortar to obtain a sheet-like positive electrode mixture. This positive electrode mixture (weight 3 mg, area 0.29 cm ² ) was pressure-bonded to a Pt mesh to obtain a positive electrode. Metal lithium having a thickness of 0.4 mm was used for the negative electrode. The electrolytic solution used was 210 mg of iodine dissolved in 12 mL of an ethylene carbonate / diethyl carbonate solution of 1 mol / L lithium perchlorate (mixing ratio 3: 7, Toyama Pharmaceutical). FIG. 6 is a discharge curve of Examples 5-7. In Example 5, the open circuit voltage was 3.73V, and the operating voltage at the time of discharge amount 0.5 mAh was 3.49V.

[Example 6]
Ketjen black 88 mg, polytetrafluoroethylene 42 mg, triphenylenephosphine sulfide (compound of chemical formula 4, manufactured by Aldrich) 200 mg were kneaded dry using a mortar to obtain a sheet-like positive electrode mixture. This positive electrode mixture (weight 3 mg, area 0.29 cm ² ) was pressure-bonded to a Pt mesh to obtain a positive electrode. Metal lithium having a thickness of 0.4 mm was used for the negative electrode. As the electrolytic solution, 195 mg of iodine was dissolved in 12 mL of an ethylene carbonate / diethyl carbonate solution of 1 mol / L lithium perchlorate (mixing ratio 3: 7, Toyama Pharmaceutical Co., Ltd.). In Example 6, the open circuit voltage was 3.78 V, and the operating voltage at the time of discharge amount 0.5 mAh was 3.64 V.

[Example 7]
Ketjen black 81 mg, polytetrafluoroethylene 50 mg and triphenylenephosphine oxide (chemical formula 8 compound, manufactured by Aldrich) 175 mg were kneaded dry using a mortar to obtain a sheet-like positive electrode mixture. This positive electrode member (weight 3 mg, area 0.29 cm ² ) was pressure-bonded to a Pt mesh to obtain a positive electrode. Metal lithium having a thickness of 0.4 mm was used for the negative electrode. As the electrolytic solution, 195 mg of iodine was dissolved in 12 mL of an ethylene carbonate / diethyl carbonate solution of 1 mol / L lithium perchlorate (mixing ratio 3: 7, Toyama Pharmaceutical Co., Ltd.). In Example 7, the open circuit voltage was 3.73 V, and the operating voltage at the time of discharge amount 0.5 mAh was 3.43 V.

[Example 8]
35 mg of ketjen black, 15 mg of polytetrafluoroethylene and 50 mg of polycyclic thiophene compound monflower (compound of chemical formula 2) were kneaded dry using a mortar to obtain a sheet-like positive electrode mixture. The positive electrode mixture (weight 3 mg, area 0.29 cm ² ) was pressure-bonded to a Pt mesh to obtain a positive electrode. As the electrolytic solution, a solution in which 220 mg of iodine was dissolved in 12 mL of an ethylene carbonate / diethyl carbonate solution of 1 mol / L lithium perchlorate (mixing ratio 3: 7, Toyama Pharmaceutical) was used. The open circuit voltage was 3.813V. The polycyclic thiophene compound monflower was synthesized as follows. To a THF solution (15 mL) of the tetramer (1.03 g) synthesized in Example 2, a THF / ethylbenzeneheptane solution of lithium diisopropylamide (2M, 31.2 mL) was added dropwise at -78 ° C. After stirring for 1 hour, sulfur (1.65 g) was added, the temperature was gradually raised to room temperature, and the mixture was stirred overnight. 200 mL of diethyl ether was added, the aqueous layer was separated, and the organic layer was extracted with water. A 5N hydrochloric acid solution was added dropwise to the combined aqueous layer. The ocherous solid obtained here was filtered, washed with diethyl ether, and then dried under reduced pressure. Next, pyrolysis reaction and sublimation purification were performed using a tubular furnace. First, this solid was heated at 450 ° C. under normal pressure to remove excess sulfur and a side reaction product having a low sublimation point, and then heated under reduced pressure (1.2 Pa) at 480 ° C. A solid was obtained. FIG. 7 is a discharge curve of Example 8 and Comparative Example 3. In Example 8, the open circuit voltage was 3.78 V, and the operating voltage at the time of discharge amount 1.0 mAh was 3.66 V.

(Results and discussion)
When the negative electrode is metallic lithium and the ion conductive medium contains iodine, it is considered that the reaction represented by the above reaction formula (1) occurs at the negative electrode and the reaction formula (2) occurs at the positive electrode. Since the standard electrode potential of lithium is −3.04 V and the standard electrode potential of iodine is +0.53 V, the theoretical maximum value of the operating voltage is 3.57 V. On the other hand, in Examples 1 to 8 in which a compound containing sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus having a lone electron pair bonded to oxygen is included in the positive electrode, FIGS. As shown, the initial voltage was higher than the theoretical value. In particular, in Examples 1, 2, 4 to 6, 8, it was found that discharging was performed while maintaining the high potential. This is probably because dissolved iodine formed a molecular complex with a compound having an element having a lone pair of electrons, thereby realizing a specific behavior and a high potential discharge that were not expected.

  10 nonaqueous electrolyte iodine battery, 12 negative electrode, 13 positive electrode, 14 compound, 15 conductive material, 16 binder, 17 current collector, 18 ion conductive medium, 20 beaker cell, 21 beaker, 22 positive electrode, 24 negative electrode, 26 electrolyte, 28 lid.

Claims (3)

A positive electrode comprising at least one compound containing at least one of phosphorus bonded to sulfur having a lone electron pair, phosphorus having a lone electron pair, and phosphorus bonded to oxygen having a lone electron pair;
A negative electrode,
A non-aqueous ion conducting medium in which iodine is dissolved and interposed between the positive electrode and the negative electrode;
A non-aqueous electrolyte iodine battery.   The nonaqueous electrolyte iodine battery according to claim 1, wherein the compound forms a molecular complex with iodine dissolved in the ion conductive medium. Any one or more, non-aqueous electrolyte iodine cell according to claim 1 or 2 of the compound of the compound, chemical formula (1) to (3).