JP5589821B2 - Electric storage device and method for manufacturing electrode active material - Google Patents

Description

  The present invention relates to an electricity storage device and a method for producing an electrode active material.

Conventionally, as an electricity storage device, a high-capacity battery is expected to use sulfur having an extremely high theoretical capacity density of 1672 Ah / kg as an electrode active material. The basic structure of an electricity storage device using sulfur is relatively simple, using a mixture of sulfur, a conductive additive carbon and a binder for the positive electrode, using metallic Li or a material containing it for the negative electrode, and LiPF for the electrolyte. An ether-based organic electrolyte in which a supporting salt such as ₆ is dissolved is used. In the electricity storage device, the solubility of the positive electrode active material sulfur and the reaction product polysulfide ions in the electrolytic solution is high, so the capacity reduction and the reaction with the elution and reaction with the negative electrode (hereinafter also referred to as the shuttle effect) A decrease in charge / discharge efficiency is a problem. As a prevention method for this, for example, in Patent Document 1, carbon and sulfur are the main constituent elements, disulfide is bonded to the carbon chain, and the weight ratio of sulfur is increased as much as possible to increase the capacity and capacity retention rate in the charge / discharge cycle. Improvements have been proposed. Patent Document 2 proposes a polysulfurized carbon having a sulfur ratio of 67% by weight or more and a total of carbon and sulfur of 95% by weight or more as an active material and further improved cycle characteristics. Non-Patent Document 1 proposes a ladder polymer in which the main chain of conductive polyaniline is connected by disulfide. Non-Patent Document 2 proposes a method for immobilizing sulfur by reacting polyacrylonitrile, which is a linear polymer not containing aromatics, with sulfur, and then cyclizing the carbon chain. Yes.

JP 2002-154815 A JP 2003-123758 A

Journal of Electrochemical Society 144, L173, 1997 Journal of Electroanalytical Chemistry 573, 121-128, 2004

  However, when single sulfur is used, two electrons are exchanged during redox, whereas in the electric storage devices described in Patent Documents 1 and 2 and Non-Patent Documents 1 and 2, sulfur is combined with carbon. For this reason, only one electron is transferred during oxidation-reduction, and the capacity may be reduced. In addition, there is a problem that the capacity per unit weight is reduced because a portion not directly related to the redox reaction, that is, energy storage, such as a carbon chain increases. For example, in Patent Documents 1 and 2, an attempt is made to further increase the sulfur component, to form a sulfide bond between sulfurs, and to increase the sulfur component that is not bonded to carbon. As in the case of using simple sulfur, it was considered that a problem of dissolution of the active material occurred, causing a decrease in charge / discharge efficiency and a decrease in capacity during cycling. Further, in Non-Patent Document 1, in poly (2,2′-dithiodianiline), the theoretical capacity is 330 Ah / kg even when the redox of the polyaniline part is used, and the experimental capacity is 270 Ah / kg per active material. The theoretical capacity of sulfur alone is 1672 Ah / kg, which is significantly lower than 670 Ah / kg in the case of a 50 wt% sulfur positive electrode. Non-Patent Document 2 states that a high-capacity material can be produced. However, the sulfur concentration is the best with only 35% by weight. This is because 15% by weight of nitrogen which cannot be combined with sulfur is contained, and therefore the capacity is not sufficient. In addition, when the capacity is increased, the energy efficiency may decrease.

  This invention is made | formed in view of such a subject, and it aims at providing the manufacturing method of the electrical storage device and electrode active material which can raise energy efficiency more, suppressing the fall of a capacity | capacitance. .

  As a result of diligent research to achieve the above-mentioned object, the present inventor uses a compound having a bond between a carbon skeleton and selenium and having a weight ratio of selenium in the compound of 15% or more as an electrode active material. As a result, an energy storage device was produced. As a result, it was found that energy efficiency could be improved, and the present invention was completed.

  That is, the electricity storage device of the present invention uses a chalcogen compound having a bond between a carbon skeleton and a chalcogen containing at least selenium, and the weight ratio of selenium to the total amount of carbon, hydrogen, nitrogen and chalcogen is 15% or more as an electrode active material. It is what.

  The method for producing an electrode active material according to the present invention is a method for producing an electrode active material used for an electrode of an electricity storage device, wherein the sulfur compound of a sulfur compound having a bond between a carbon skeleton and sulfur is replaced with selenium. It includes a process.

  The method for producing an electricity storage device and an electrode active material of the present invention can further improve energy efficiency while suppressing a decrease in capacity. The reason why such an effect is obtained is not clear, but is presumed as follows. For example, since the chalcogen element is bonded to a carbon skeleton such as a polycyclic aromatic ring, it is possible to prevent the chalcogen from dissolving in the electrolyte solution, which is a problem when using the chalcogen alone, and the shuttle effect due to the dissolved chalcogen, Capacity reduction can be suppressed. In addition, the carbon skeleton to which the chalcogen element is bonded is presumed to have a structure in which molecules are stacked due to intermolecular interactions such as van der Waals force and π-π interaction. When the interlayer distance increases due to the above, it is assumed that a large capacitance like an electric double layer capacitor or Li intercalation appears. When chalcogen is immobilized, only one-electron redox can occur, and lowering the capacity becomes a problem. However, in the present invention, it is possible to superimpose the above-described carbon skeleton capacitance. is there. For this reason, in addition to the capacity associated with the redox of the chalcogen bonded to the carbon skeleton, the capacity can be improved by a novel mechanism that has not been used so far, in which the capacitance of the carbon skeleton due to the redox of the chalcogen is superimposed. Inferred. In addition, since at least selenium is included as the chalcogen, the capacity may be slightly lower than that including only sulfur as the chalcogen, but it is presumed that the conductivity of the active material is increased and the energy efficiency can be increased. The carbon skeleton preferably has an aromatic ring structure, and the aromatic ring may be a carbon-based aromatic, and at least one or more aromatic rings may contain sulfur, selenium, nitrogen, oxygen, and the like. It is good also as a thing containing the heterocyclic ring to contain.

Explanatory drawing of the evaluation cell 10. FIG. The Raman spectrum of Examples 1-6 and Comparative Examples 1 and 3-5. The graph which shows the charge / discharge waveform of Examples 1, 2 and Comparative Example 1. The graph which shows the result of the cyclic voltammetry of Example 1 and Comparative Example 1. The graph which shows the relationship between the temperature of Example 1 and Comparative Example 1 and discharge capacity.

  The electricity storage device of the present invention uses, as an electrode active material, a chalcogen compound that has a bond between a carbon skeleton and a chalcogen containing at least selenium, and the weight ratio of selenium to the total amount of carbon, hydrogen, nitrogen, and chalcogen is 15% or more. . Here, chalcogen refers to a group 16 element excluding oxygen, and specifically, sulfur (S), selenium (Se), tellurium (Te), and polonium (Po). The carbon skeleton refers to a structure having a plurality of carbons (C) in the structure, and the skeleton may be formed by a bond of only carbon, or the skeleton may be formed by a bond between carbon and another element. May be formed. The carbon skeleton may be linear (may be linear or branched) or cyclic, but is preferably cyclic, and more preferably a series of a plurality of cyclic structures. The carbon skeleton is preferably conductive. As such a carbon skeleton, those having an aromatic ring structure are preferable, and those having a structure in which a plurality of aromatic rings are connected are particularly preferable. In this electricity storage device, for example, a chalcogen compound as an electrode active material may be used as a positive electrode active material or a negative electrode active material. That is, an electricity storage device of the present invention includes a positive electrode having the chalcogen compound as a positive electrode active material, a negative electrode having a negative electrode active material, and an ion conductive medium that is interposed between the positive electrode and the negative electrode to conduct ions. It is good. In addition, an electricity storage device of the present invention includes a positive electrode having a positive electrode active material, a negative electrode having the chalcogen compound as a negative electrode active material, and an ion conductive medium that is interposed between the positive electrode and the negative electrode and conducts ions. It may be a thing. The conducting ions may be, for example, ions of Group 1 elements such as lithium, sodium and potassium, and ions of Group 2 elements such as magnesium and calcium. Among these, lithium ion is preferable from the viewpoint of energy density. Here, the case where the chalcogen compound having a carbon skeleton having a structure in which a plurality of aromatic rings are connected is used as a positive electrode active material, and the ion conductive medium conducts lithium ions will be mainly described.

  In the electricity storage device of the present invention, the chalcogen compound has a plurality of aromatic rings. Here, it is considered that the chalcogen compound has electron conductivity and contributes to redox electron transport of the chalcogen element. Chalcogen compounds are presumed to have a stacked structure due to intermolecular interactions such as van der Waals forces and π-π interactions, and the distance between chalcogen compounds increases due to the formation of anions. In such a case, it is considered that a large capacitance like an electric double layer capacitor or Li intercalation appears. This aromatic ring may include a five-membered ring or a six-membered ring. The aromatic ring may include a carbon-based aromatic ring (for example, a benzene ring), or a heterocyclic ring (for example, thiophene) containing one or more of sulfur, selenium, nitrogen, and oxygen in the ring structure. Ring or pyridine ring). Alternatively, a structure in which aromatic rings are connected by a heterocyclic ring may be used. For example, a structure in which benzene skeletons are connected by a dithian-like skeleton is preferable. The dithian-like skeleton includes not only the dithian skeleton but also those in which the sulfur of the dithian skeleton is another chalcogen. Further, a structure in which polycyclic aromatics are connected by a heterocyclic ring may be used. For example, a structure in which anthracene skeletons are connected by a dithian-like skeleton is preferable. As this polycyclic aromatic, for example, in the six-membered ring, those having an anthracene structure and phenanthrene structure, those having a tetracene structure, pyrene structure, triphenylene structure, tetraphen structure and chrysene structure, pentacene structure, picene structure and perylene The thing etc. which have a structure are mentioned. For example, “having an anthracene structure” includes anthracene, anthracene derivatives having a substituent bonded to anthracene, and those having a five-membered ring compound bonded to anthracene. Examples of the substituent include an alkyl group, a hydroxyl group, and halogen. Of these, the aromatic ring preferably includes any one of a structure in which naphthalene and thiophene are linked, an anthracene structure, a tetracene structure, and a pentacene structure, in consideration of handling and availability. The aromatic ring preferably has a structure capable of bonding as many chalcogen elements as possible. For example, a polyacene structure in which benzene skeletons are arranged in a row is preferable. In the present invention, the capacity increases due to the superposition of the capacitor component of the polycyclic aromatic moiety generated by redox of the chalcogen substituent, so that the polycyclic aromatic structure has many edges so that more chalcogen substituents can be bonded. This is because it is considered preferable. The polyacene structure has a skeleton in which aromatic rings are one-dimensionally linked, and it may be composed only of carbon, or may contain elements other than carbon (for example, sulfur, nitrogen and oxygen). Good.

  In the electricity storage device of the present invention, the chalcogen compound may contain selenium as the chalcogen. If selenium is included, it is considered that the redox polarization is reduced by increasing the conductivity of the active material and the like, and the charge / discharge potential difference can be reduced, that is, the energy efficiency can be increased. Here, the electrode active material may contain only selenium, or may contain selenium and sulfur. Further, tellurium or polonium may be included. Those containing only selenium can lower the operating voltage than those containing selenium and sulfur, and can be used more favorably as a negative electrode active material, for example, in combination with a positive electrode active material that operates at a high voltage. It is. On the other hand, those containing selenium and sulfur are preferable in that the discharge capacity can be increased. Moreover, since an operating voltage is higher than what contains only selenium, it can be used more suitably as a positive electrode active material, for example.

In the electricity storage device of the present invention, the chalcogen compound may have a weight ratio of selenium to the total amount of carbon, hydrogen, nitrogen and chalcogen of 15% or more, preferably 20% or more, and preferably 30% or more. Is more preferable. If selenium is 15% or more, energy efficiency can be improved as compared with selenium less than 15%. Further, the redox capacity of chalcogen is increased, and electrostatic repulsion during reduction is not reduced too much, and the capacity as a capacitor is also exhibited. For this reason, the discharge capacity can be increased by superimposing these capacities. The upper limit of the weight ratio of selenium is not particularly limited as long as it is in a range that can be bonded to the carbon skeleton, but for example, it is preferably 77% or less corresponding to the C ₂ Se composition in which all of selenium is bonded to the outer periphery of the polyacene structure. When the weight ratio of selenium is within a range in which selenium and the carbon skeleton can be combined, it is possible to suppress the occurrence of the shuttle effect, which is a problem when using chalcogen alone, and suppress the decrease in discharge capacity. be able to. For the same reason, when a chalcogen other than selenium is included, it is preferable that all the chalcogen can be bonded to the carbon skeleton. Here, energy efficiency (%) is an index indicating how much electric energy required for charging can be taken out during discharging. Here, it is a value obtained by multiplying the amount of power at the time of discharging by the amount of power at the time of previous charging, multiplied by 100.

  In the electricity storage device of the present invention, the chalcogen compound has a chalcogen bonded to the carbon skeleton. The form of this bond is that the carbon skeleton has an aromatic ring structure, and in the oxidized state, one of the two bonds of the chalcogen is bonded to the aromatic ring structure and the other is a dimer with the other chalcogen element. It is preferable that a dichalcogenide bond that is a body is formed, or that two bonds of chalcogen are both bonded to an aromatic ring structure. In such a chalcogen compound, it is considered that only one of the two bonds is an anion bonded to the aromatic ring structure in the reduced state. At this time, since the anion is delocalized in the bonded polycyclic aromatic compound, the intermolecular distance of the polycyclic aromatic compound spreads due to electrostatic repulsion, and the solvent and Li ions can enter the interlayer, The specific surface area increases at a stretch. Therefore, the reduction of the chalcogen element significantly increases the capacitance as a capacitor, which is superimposed on the discharge capacity derived from the chalcogen, so that a large capacity can be expressed.

  Here, a specific example of the chalcogen compound used for the electrode active material of the electricity storage device will be described. Examples of the chalcogen compound of the present invention include those represented by the following formula (1) having a polyacene structure in which pyridine rings having chalcogen bonded to the outer periphery are arranged in a line (hereinafter also referred to as PAN system). Examples of the chalcogen compound include those represented by the following formula (2) having a polyacene structure in which a naphthalene skeleton is connected by two thiophene-like skeletons which are aromatic heterocycles (hereinafter also referred to as PNV system). Here, the thiophene-like skeleton includes not only the thiophene skeleton but also those in which sulfur of thiophene is other chalcogen. Examples of the chalcogen compound include those represented by the following formula (3) having a structure in which a chalcogen is bonded to the outer periphery of a polyacene structure in which an anthracene skeleton is connected by a heterocyclic dithian-like skeleton (hereinafter also referred to as AN system). Examples of the chalcogen compound include those represented by the following formula (4) having a polyacene structure in which a benzene skeleton is connected by a heterocyclic dithian-like skeleton and a thiophene-like skeleton (hereinafter also referred to as a PPS system). Examples of the chalcogen compound include those represented by the following formula (5) having a polyacene structure in which a naphthopylene skeleton having a chalcogen bonded to the outer periphery is connected by two thiophene-like skeletons which are aromatic heterocyclic rings (hereinafter also referred to as NPY type). Called). Examples of the chalcogen compound include those represented by the following formula (6) having a structure in which chalcogen is bonded to the outer periphery of the pentacene skeleton (hereinafter also referred to as a PEN system). In the formulas (1) to (6), CG represents a chalcogen element. Moreover, Formula (1)-(6) is what chalcogen couple | bonded ideally, and there may be less chalcogen than this.

  In the electricity storage device of the present invention, the positive electrode is prepared by, for example, mixing a positive electrode active material, a conductive material, and a binder, and adding a suitable solvent to form a paste-like positive electrode material on the surface of the current collector. However, it may be compressed to increase the electrode density as necessary. The positive electrode active material can be the chalcogen compound described above.

  In the electricity storage device of the present invention, the negative electrode is prepared by, for example, mixing a negative electrode active material, a conductive material, and a binder, and adding a suitable solvent to form a paste-like negative electrode material on the surface of the current collector. However, it may be compressed to increase the electrode density as necessary. The negative electrode active material preferably contains a metal or metal ion. The negative electrode active material may include a material that absorbs and releases lithium. Here, examples of the material that occludes and releases lithium include metal oxides, metal sulfides, metal nitrides, and carbonaceous substances that occlude and release lithium, in addition to metal lithium and lithium alloys. Examples of the lithium alloy include alloys of lithium with aluminum, silicon, tin, magnesium, indium, calcium, and the like. Examples of the metal oxide include tin oxide, silicon oxide, lithium titanium oxide, niobium oxide, and tungsten oxide. Examples of the metal sulfide include tin sulfide and titanium sulfide. Examples of the metal nitride include lithium nitride. Examples of the carbonaceous material that occludes and releases lithium include graphite, coke, mesophase pitch-based carbon fiber, spherical carbon, and resin-fired carbon. For this negative electrode, a current collector, a conductive material, and a binder can be used as appropriate as in the case of the positive electrode.

  In the electricity storage device of the present invention, the conductive material used for the positive electrode and the negative electrode is not particularly limited as long as it is an electron conductive material that does not adversely affect the battery performance. For example, natural graphite (scale graphite, flake graphite) or artificial Graphite such as graphite, acetylene black, carbon black, ketjen black, carbon whisker, needle coke, carbon fiber, or a mixture of one or more of metals (copper, nickel, aluminum, silver, gold, etc.) Can be used. Among these, carbon black, ketjen black, and acetylene black are preferable as the conductive material from the viewpoints of electron conductivity and coatability. The binder serves to bind the active material particles and the conductive material particles. For example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorine-containing resin such as fluorine rubber, or polypropylene, Thermoplastic resins such as polyethylene, ethylene-propylene-dienemer (EPDM), sulfonated EPDM, natural butyl rubber (NBR) and 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. Examples of the solvent for dispersing the active material, the conductive material, and the binder include ethanol, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, and N, N-dimethylamino. Organic solvents such as propylamine, ethylene oxide, and tetrahydrofuran can be used. Moreover, a dispersing agent, a thickener, etc. may be added to water, and an active material may be slurried with latex, such as SBR. As the thickener, for example, polysaccharides such as carboxymethyl cellulose and methyl cellulose can be used alone or as a mixture of two or more. Examples of the application method include roller coating such as applicator roll, screen coating, doctor blade method, spin coating, bar coater, and the like, and any of these can be used to obtain an arbitrary thickness and shape. Current collectors include copper, aluminum, titanium, stainless steel, nickel, iron, calcined carbon, conductive polymer, conductive glass, etc., as well as aluminum and aluminum for the purpose of improving adhesion, conductivity, and oxidation resistance. What processed the surface of copper etc. with carbon, nickel, titanium, silver, etc. 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.

In the electricity storage device of the present invention, the ion conductive medium may be a solution in which a supporting salt is dissolved in a solvent. The supporting salt is not particularly limited as long as it is a lithium salt used in a normal lithium secondary battery. For example, lithium bis (trifluoromethanesulfonyl) imide (LiTFSI), Li (C ₂ F ₅ SO ₂ ) Known supporting salts such as ₂ N, LiPF ₆ , LiClO ₄ , and LiBF ₄ can be used. These may be used alone or in combination. The solvent of the ion conductive medium is not particularly limited, but carbonates such as ethylene carbonate (EC), diethyl carbonate (DEC) and propylene carbonate (PC), ethers such as dimethoxyethane (DME), triglyme and tetraglyme, Cyclic ethers such as dioxolane (DOL) and tetrahydrofuran and mixtures thereof are preferred. Alternatively, ionic liquids such as 1-methyl-3-propylimidazolium bis (trifluorosulfonyl) imide and 1-ethyl-3-butylimidazolium tetrafluoroborate can be used. The ion conductive medium may be gelled by adding an electrolyte containing a supporting salt to a polymer such as polyvinylidene fluoride, polyethylene oxide, polyethylene glycol, polyacrylonitrile, or a saccharide such as an amino acid derivative or a sorbitol derivative. .

  The electricity storage device 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 can withstand the range of use of the electricity storage device. For example, a polymer nonwoven fabric such as a polypropylene nonwoven fabric or a polyphenylene sulfide nonwoven fabric, a microporous film of an olefin resin such as polyethylene or polypropylene, And polyimide three-dimensional porous film. These may be used alone or in combination.

  The shape of the electricity storage device of the present invention is not particularly limited, and examples thereof include a coin cell type, a wound battery type, a laminate 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.

  The electricity storage device of the present invention is preferably subjected to aging treatment in the range of 0.5 V or less on the basis of the Li potential in the initial charge and discharge on the electrode provided with the electrode active material. In this way, the capacity can be further increased.

  Next, the manufacturing method of the electrode active material containing the chalcogen compound mentioned above is demonstrated. This manufacturing method may include a sulfuration step, a sulfur removal step, a selenization step, and a selenium removal step. In the sulfurization step, a compound capable of forming the above-described carbon skeleton (hereinafter also referred to as a raw material compound) and sulfur are mixed and heated to synthesize a sulfur compound. Examples of the raw material compound include polyacrylonitrile (PAN), polyphenol, poly-2,6-naphthalene vinylene (PNV), poly-p-phenylene sulfide (PPS), poly-p-phenylene vinylene, naphtho [2, 3-a] pyrene (NPY), polyaniline, and the like can be used. Moreover, when a polycyclic aromatic compound such as anthracene (AN) or pentacene (PEN) and sulfur are heated and fired as a raw material compound, a composite material in which a polycyclic aromatic structure bonded with sulfur is connected by a dithian skeleton is obtained. Can do. The raw material compound is preferably thermosetting. This is because it is considered that sulfur and the raw material compound can be mixed uniformly. The mixing ratio is not particularly limited, but it is preferable that the amount of sulfur is more than the amount of sulfur that can be bonded to the carbon skeleton. The heating temperature is not particularly limited, but is preferably a temperature equal to or higher than the melting point of sulfur. For example, the temperature may be 300 ° C. or higher and 350 ° C. or lower. The heating time can be determined empirically such as 3 hours or more. The atmosphere during heating is not particularly limited, but is preferably an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere. In this sulfuration step, stirring may be performed during heating. In particular, when a thermoplastic raw material compound is used, it is preferable to stir because both sulfur and the raw material compound melt and are difficult to mix uniformly. By such a sulfuration process, a sulfur compound having a bond between the carbon skeleton and sulfur is obtained. Then, the sulfur removal process which removes the elemental sulfur remaining in the sulfur compound obtained in the sulfurization process is performed. In the sulfur removal step, the product obtained in the sulfuration step is heated at a temperature higher than that in the sulfuration step. Although heating temperature should just be temperature higher than a sulfuration process, it can be made into 450 to 500 degreeC, for example. The heating time can be determined empirically such as 3 hours or more. The atmosphere during heating is not particularly limited, but is preferably an inert atmosphere such as a nitrogen atmosphere or an argon atmosphere. By such a sulfur removal step, a sulfur compound from which simple sulfur is removed is obtained. In addition, when the removal of elemental sulfur is not sufficient with one heating, the heating time may be lengthened, the heating temperature may be increased, or cooling and heating may be performed again after the heating described above. The heating and cooling may be repeated as necessary. Subsequently, in the selenization step, sulfur of the obtained sulfur compound is replaced with selenium. Specifically, a sulfur compound and selenium are mixed and heated to synthesize a selenium compound. Here, the selenium compound is assumed to be selenized in part or all of sulfur. The heating temperature, heating time, heating atmosphere, and the like can be appropriately determined as in the sulfuration step. Moreover, it is good also as what stirs at the time of a heating similarly to a sulfuration process. The selenium removal step can be performed in the same manner as the sulfur removal step. In addition, the manufacturing method of the electrode active material of this invention should just include a selenization process. For example, a sulfur compound prepared in advance may be used by omitting the sulfurization step. Moreover, it is good also as what does not perform a sulfur removal process and a selenium removal process by making the amount of sulfur and the amount of selenium appropriate. Moreover, although the sulfur removal process and the selenium removal process are performed by heating, they may be removed with a good solvent of sulfur or selenium. Examples of the good solvent for sulfur and selenium include carbon disulfide.

  In the manufacturing method described above, the sulfur compound is selenized, but the raw material compound may be directly selenized. That is, it may include a selenization step in which a compound capable of forming a carbon skeleton and selenium are mixed and heated to synthesize a selenium compound. In this way, since a chalcogen compound containing no sulfur is obtained, for example, a chalcogen compound suitable for use as a negative electrode active material can be obtained more easily. Note that since selenium has a high melting point and low activity, the selenium concentration may not be higher than a certain level only by mixing and heating. For this reason, the selenium concentration can be increased more easily by selenizing a sulfur compound prepared in advance.

  Here, the capacity development mechanism of the electrode active material of the electricity storage device of the present invention will be considered. The chalcogen compound, which is the electrode active material of the present invention, is presumed to have a structure in which molecules are stacked due to intermolecular interactions such as van der Waals force and π-π interaction. When this electrode active material is used for the positive electrode, the chalcogen becomes a chalcogen anion due to reduction of the chalcogen substituent during discharge. At this time, the anion is delocalized in the bonded polycyclic compound, the intermolecular distance of the polycyclic compound is widened by electrostatic repulsion, the solvent and Li ions are likely to enter the interlayer, and the specific surface area increases at a stretch. It is done. Therefore, the reduction of the chalcogen atoms significantly increases the capacitance as a capacitor, and this is superposed on the discharge capacity derived from the chalcogen, so that it is assumed that a large capacity is developed. In addition, the oxidation-reduction potential of chalcogen is about 2V with respect to the Li electrode, whereas it is slightly over 3V for carbon. Therefore, when the capacitance increases at a stretch in the vicinity of 2V, a capacity corresponding to the voltage difference between the open circuit voltage of 3V or more and the reduction potential of sulfur of about 2V is immediately developed in the vicinity of 2V. A constant-voltage discharge similar to a battery (charge that is negatively charged as a capacitor) occurs. The reverse phenomenon occurs reversibly during charging. Therefore, the electricity storage device of the present invention can express a much larger capacity than the capacity expected from the chalcogen content, and is considered to be an epoch-making electricity storage device with a mechanism that has not existed before. When this chalcogen is all sulfur, the charge / discharge voltage difference is relatively large, the oxidation and reduction potential difference is large in the cyclic voltammetry (CV) waveform, large polarization occurs, and the energy efficiency may be low. In contrast, in polycyclic aromatic compounds to which chalcogen containing at least selenium is bonded, the electrical conductivity is increased, so that the charge / discharge potential difference can be reduced and the energy efficiency is improved as compared with the composite material containing only sulfur. . Further, the present invention shows a feature that charging and discharging can be performed while suppressing a decrease in capacity even at a low temperature such as −30 ° C., which is difficult with conventional batteries. In addition, when the chalcogen is composed only of selenium, the discharge potential is lowered to around 1.5 V, which is suitable for the negative electrode material of the battery. When used as a negative electrode material for a battery, it is preferable in that it has a high capacity and can prevent the problem of Li metal dendrite precipitation, which is a problem with Li-based negative electrodes. Even when the chalcogen is composed only of selenium, it can be used for the positive electrode. This is because the charge / discharge potential difference can be reduced and energy efficiency can be improved.

  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 electrical storage device of this invention concretely is demonstrated as an Example.

[Example 1] (PANSe)
1 g of polyacrylonitrile (PAN, manufactured by Aldrich) and 5 g of selenium powder (about 10 μm, 99.9%, manufactured by High-Purity Chemical) were added and mixed well. The test tube was placed in an annular furnace in a nitrogen stream and heated to 300 ° C. over 1 hour. After heating for 3 hours to selenize PAN, the temperature was raised to 450 ° C. over 30 minutes and left for 3 hours to remove excess selenium. After cooling to room temperature, the black mass was taken out, placed on an alumina boat, and heated at 450 ° C. for 3 hours under a nitrogen stream to further remove excess selenium to obtain a black powder sample (chalcogen compound). This is hereinafter referred to as PANSe. 70% by weight of this PANSe, 20% by weight of carbon (ECP600JD, manufactured by Lion), 10% by weight of polytetrafluoroethylene (PTFE) as a binder, and knead well in a mortar until it becomes bowl-shaped And molded into a sheet. This sheet was cut into a circular shape with a diameter of 12 mm and vacuum dried to obtain a positive electrode material. Using this positive electrode material, lithium metal as a negative electrode, porous polyethylene as a separator, and electrolytic solution (ethylene carbonate EC + diethyl carbonate DEC (volume ratio 3: 7) containing 1M-LiPF ₆ ) of FIG. An evaluation cell was created. This obtained evaluation cell was defined as Example 1. Note that the Li metal was a Li plate having a thickness of 0.4 mm and a diameter of 18 mm, and the weight of the positive electrode material was 3 mg and the electrode area was 1.3 cm ² .

  1A and 1B are explanatory views of the evaluation cell 10, FIG. 1A is a cross-sectional view before the evaluation cell 10 is assembled, and FIG. 1B is a cross-sectional view after the evaluation cell 10 is assembled. An evaluation cell 10 was produced in a glove box under an argon atmosphere. In assembling the evaluation cell 10, first, a negative electrode 16 and a polyethylene separator 18 (a microporous polyethylene film, a microporous polyethylene film, a cavity 14 provided in the center of the upper surface of a stainless steel cylindrical substrate 12 with a thread groove engraved on the outer peripheral surface thereof. Tonen Chemical Co., Ltd.) and the positive electrode 20 were laminated in this order while injecting an appropriate amount of a non-aqueous electrolyte into the cavity 14. Further, an insulating ring 29 made of polypropylene is inserted, and then a conductive column 24 fixed in a liquid-tight manner in the hole of the insulating ring 22 is disposed on the positive electrode 20, and a conductive cup-shaped lid 26 is formed on the cylinder. Screwed into the substrate 12. Further, an insulating resin ring 27 is disposed on the cylinder 24, and a pressure bolt 25 having a through hole 25a is screwed into a screw groove carved in an inner peripheral surface of an opening 26a provided at the center of the upper surface of the lid 26, The negative electrode 16, the separator 18, the solid electrolyte membrane 18, and the positive electrode 20 were pressed and adhered. Thus, the evaluation cell 10 was produced. Since the cylinder 24 is positioned below the upper surface of the ring 22 and is in contact with the lid 26 via the insulating resin ring 27, the lid 26 and the cylinder 24 are in an electrically non-contact state. In addition, since the packing 28 is disposed around the cavity 14, the electrolyte injected into the cavity 14 does not leak to the outside. In this evaluation cell 10, the lid 26, the pressure bolt 25, and the cylindrical base 12 are integrated with the negative electrode 16, so that the whole becomes the negative electrode side, and the column 24 is integrated with the positive electrode 20 and insulated from the negative electrode 16. Therefore, it becomes the positive electrode side. Thus, an evaluation cell was created.

(Elemental analysis)
Elemental analysis was performed on the obtained sample (chalcogen compound). The elemental analysis of CHN was performed by a combustion method using a fully automatic elemental analyzer (manufactured by Elemental, VarioEL). The sulfur was analyzed by flask combustion-ion chromatography. The system for sulfur analysis was DX320 manufactured by Dionex, the column was IonPacAS12A, and the mobile phase was Na ₂ CO ₃ (2.7 mmol / L) / NaHCO ₃ (0.3 mmol / L). The analysis of selenium was performed as follows. First, the sample was weighed in a sealed container, thermally decomposed with nitric acid and perchloric acid with salt added, and made up to a constant volume with water. For this solution, Se was measured by ICP emission spectrometry, and the content in the sample was determined.

(Raman spectrum analysis)
The obtained sample (chalcogen compound) was subjected to Raman spectroscopic measurement. The Raman spectrum analysis was measured using a laser Raman spectroscopy system (manufactured by JASCO Corporation, NRS-3300). Perform Raman spectroscopy with an excitation light having a wavelength of 532 nm, a complex containing a sulfur seen from 1200 cm ^-1 vicinity derived from an aromatic ring skeleton vibration peaks up 1600 cm ^-1 vicinity, and of 1020 cm ^-1 vicinity near 1050 cm ^-1 A peak derived from the ring was observed.

(Evaluation of electrochemical properties)
The electrochemical characteristics of the obtained evaluation cell were evaluated. In the evaluation of electrochemical characteristics, the discharge capacity per unit weight (mAh / g), energy efficiency (%), discharge voltage (V) at SOC 0.5, charge / discharge in the sample (chalcogen compound) as the electrode active material The voltage difference (V), voltage loss (%), and low temperature characteristics were examined. First, the evaluation cell was installed in a constant temperature bath at 25 ° C., and 0.5 mA constant current charging / discharging was performed twice in the region from 0.5 V to 3.0 V as initial aging at this temperature. After that, as a charge / discharge test, 0.5 mA constant current charge / discharge is performed in the region from 0.7 V to 2.8 V, and the discharge capacity (mAh / g) at this time, the electric energy during discharge (W, hereinafter also referred to as WD). ), The amount of electric power (W, hereinafter also referred to as WC) at the time of the previous charging, the charging voltage (V, hereinafter also referred to as VC0.5) and the discharging voltage (V, hereinafter also referred to as VD0.5) at SOC 0.5 did. In addition, after the initial aging described above, the temperature of the thermostatic chamber was changed to 25 ° C., 0 ° C., −15 ° C., −30 ° C., −45 ° C., −60 ° C., and in the region of 0.7V to 2.8V. Two levels of low current charge and discharge at 0.1 mA and 0.5 mA were performed, and the discharge capacity (mAh / g) at this time was measured. In this measurement, it was held at each temperature for 1 hour before charging / discharging. The energy efficiency E (%) was determined by the equation E = (WD / WC) × 100. The charge / discharge voltage difference (V) was a value obtained by subtracting the discharge voltage VD0.5 (V) from the charge voltage VC0.5 (V). Moreover, the voltage loss L (%) was calculated | required by the type | formula of L = {(VC0.5-VD0.5) /VD0.5} * 100.

[Example 2] (PANSSe)
1 g of PAN and 5 g of sulfur powder (75 μm or less, 99.99%, manufactured by High Purity Chemical) were added and mixed well, and the mixture was put into a test tube. The test tube was placed in an annular furnace in a nitrogen stream and heated to 300 ° C. over 1 hour. After heating for 3 hours to sulfinate PAN, the temperature was raised to 450 ° C. over 30 minutes and left for 3 hours to remove excess sulfur. After cooling to room temperature, a black sample powder was obtained. Hereinafter, this is referred to as PANS. 200 mg of this PANS and 1 g of selenium powder were mixed and put into a test tube. The test tube was placed in an annular furnace in a nitrogen stream and heated to 300 ° C. over 1 hour. After the PANS was selenized by heating for 3 hours, the temperature was raised to 450 ° C. over 30 minutes and left for 3 hours to remove excess selenium. After cooling to room temperature, the black mass was taken out, placed on an alumina boat, and heated at 450 ° C. for 3 hours under a nitrogen stream to further remove excess selenium to obtain a black sample powder. Hereinafter, this is referred to as PANSSe. Using the obtained PANSSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Example 2.

[Example 3] (PNVSe)
Sample powder was obtained through the same steps as in Example 1 except that 0.5 g of poly-2,6-naphthalene vinylene (PNV, manufactured by Aldrich) was used instead of PAN, and 2.5 g of selenium powder was added. Hereinafter, this is referred to as PNVSe. Using the obtained PNVSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Example 3.

[Example 4] (PNVSSe)
Sample powder was obtained through the same steps as in Example 2 except that 0.5 g of PNV was used instead of PAN, and 2.5 g of sulfur powder was added to synthesize PNVS. Hereinafter, this is referred to as PNVSSe. Using the obtained PNVSSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Example 4.

Example 5 (ANSSe)
Sample powder was obtained through the same steps as in Example 2 except that 1 g of anthracene (AN, manufactured by Aldrich) was used instead of PAN, and 5 g of sulfur powder was added to synthesize PANS. Hereinafter, this is referred to as ANSSe. Using the obtained ANSSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Example 5.

[Example 6] (PPSSSe)
Sample powder was obtained through the same steps as Example 2 except that 1 g of poly-p-phenylene sulfide (PPS, manufactured by Aldrich) was used instead of PAN, and 5 g of sulfur powder was added to synthesize PPSS. Hereinafter, this is referred to as PPSSSe. Using the obtained PPSSSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Example 6.

[Comparative Example 1] (PANS)
1 g of PAN and 5 g of sulfur powder (75 μm or less, 99.99%, manufactured by High Purity Chemical) were added and mixed well, and the mixture was put into a test tube. The test tube was placed in an annular furnace in a nitrogen stream and heated to 300 ° C. over 1 hour. After heating for 3 hours to sulfurize PAN, the temperature was raised to 450 ° C. over 30 minutes and allowed to stand for 3 hours. After cooling to room temperature, a black sample powder was obtained. Hereinafter, this is referred to as PANS. An evaluation cell obtained through the same steps as in Example 1 using the obtained PANS was used as Comparative Example 1.

[Comparative Example 2] (PANSeS)
200 mg of PANSe and 1 g of sulfur powder were mixed and put into a test tube. The test tube was placed in an annular furnace in a nitrogen stream and heated to 300 ° C. over 1 hour. After heating for 3 hours to sulfinate PANSe, the temperature was raised to 450 ° C. over 30 minutes and allowed to stand for 3 hours. After cooling to room temperature, a black sample powder was obtained. Hereinafter, this is referred to as PANSeS. An evaluation cell obtained through the same steps as in Example 1 using the obtained PANSeS was used as Comparative Example 2.

[Comparative Examples 3 to 5] (PNVS, ANS, PPSS)
Sample powder was obtained through the same process as Comparative Example 1 except that 0.5 g of PNV was used instead of PAN and 2.5 g of sulfur powder was added. Hereinafter, this is referred to as PNVS. An evaluation cell obtained through the same steps as in Example 1 using the obtained PNVS was set as Comparative Example 3. Moreover, sample powder was obtained through the process similar to the comparative example 1 except having used 1 g of AN instead of PAN and adding 5 g of sulfur powder. Hereinafter, this is referred to as ANS. An evaluation cell obtained through the same steps as in Example 1 using the obtained ANS was referred to as Comparative Example 4. Moreover, sample powder was obtained through the same process as Comparative Example 1 except that 1 g of PPS was used instead of PAN and 5 g of sulfur powder was added. Hereinafter, this is referred to as PPSS. An evaluation cell obtained through the same steps as in Example 1 using the obtained PPSS was used as Comparative Example 5.

[Comparative Examples 6 and 7] (NPYSe, PENSe)
Sample powder was obtained through the same steps as in Example 1 except that 0.5 g of naphtho [2,3-a] pyrene (NPY, manufactured by Aldrich) was used instead of PAN, and 2.5 g of selenium powder was added. Hereinafter, this is referred to as NPYSe. An evaluation cell obtained through the same steps as in Example 1 using the obtained NPYSe was set as Comparative Example 6. A sample powder was obtained through the same process as in Example 1 except that 0.5 g of pentacene (PEN, manufactured by Aldrich) was used instead of PAN and 2.5 g of selenium powder was added. Hereinafter, this is referred to as PENSe. Using the obtained PENSe, an evaluation cell obtained through the same steps as in Example 1 was defined as Comparative Example 7.

(Estimation of chalcogen compound structure)
For the compounds of Examples and Comparative Examples, the structure of the raw materials used and representative basic structures of the respective chalcogen compounds (PAN, PNV, AN, PPS) estimated from the results of elemental analysis and Raman spectroscopy Table 1 shows. In Table 1, CG represents chalcogen. The estimated basic structure shown in Table 1 is a structure estimated from the elemental analysis result with the largest amount of chalcogen. Moreover, in Table 1, although the binding state in which chalcogens are connected is drawn for convenience, a disulfide-like bond (chalcogenide bond) that is a dimer is actually formed, or both are bonded to a carbon skeleton (aromatic). It was inferred that the thiocarbonyl (thioquinone) -like structure was formed. In addition, the disulfide-like bond means that the sulfur of the disulfide bond is chalcogen. Further, the thiocarbonyl-like structure means that the sulfur of the thiocarbonyl structure is chalcogen. In addition, it was speculated that chalcogen bonded to carbon becomes an anion in the reduced state. FIG. 2 is a Raman spectrum of the chalcogen compounds of Examples 1 to 6 and Comparative Examples 1 and 3 to 5. Considering the results of the Raman measurements, a plurality of peaks which are considered to be derived from an aromatic ring skeleton also between 1200 cm ^-1 or 1600 cm ^-1 or less in any of the chalcogen compound is confirmed. Further, in the chalcogen compounds of Examples 1, 2, 5 and Comparative Examples 1 and 4, a peak considered to be derived from a heterocycle containing chalcogen was confirmed between 900 cm ^{−1 and} 1100 cm ⁻¹ . That is, it was speculated that the chalcogen compounds of Examples 1, 2, 5 and Comparative Examples 1, 4 had a heterocycle containing chalcogen. Here, when chalcogen is sulfur (hereinafter also referred to as S material), sulfur is substituted with selenium (hereinafter also referred to as SSe material), and chalcogen is selenium (hereinafter also referred to as Se material), chalcogen is The peaks considered to be derived from the included heterocyclic ring are shifted to the low wavenumber side in the order of S material, SSe material, and Se material, and it was inferred that substitution to Se, which is a heavy element, has occurred. Further, in the chalcogen compounds of Examples 3, 4, 5 and Comparative Examples 3 and 4, a peak considered to be derived from the thiophene-like skeleton was confirmed in the vicinity of 1450 cm ⁻¹ . That is, the chalcogen compounds of Examples 3, 4 and 5 and Comparative Examples 3 and 4 were presumed to have a thiophene-like skeleton. In addition, in the chalcogen compounds of Example 6 and Comparative Example 5, a peak considered to be derived from a heterocyclic ring containing chalcogen and a peak considered to be derived from a thiophene-like skeleton could not be confirmed. This was presumed to be because it could not be confirmed by Raman spectroscopic analysis due to the small number of repetitions of the basic structure (for example, 2 or less) and the structure in which a small aromatic ring was connected to a large aromatic skeleton. Table 2 shows the elemental analysis results of Examples 1 to 6 and Comparative Examples 1 to 7. From Table 2, it was found that in Examples 1 to 6, the weight ratio of selenium to the total amount of carbon, hydrogen, nitrogen and chalcogen was 15% or more. Table 3 shows the element ratios of sulfur and selenium with respect to the total amount of carbon, hydrogen, nitrogen and chalcogen in Examples 2, 4, 5, and 6 that are SSe materials and Comparative Examples 1, 3, 4, and 5 that are S materials. Show. From Table 3, the sum of the element ratios of sulfur and selenium in the SSe material was almost equal to the element ratio of sulfur in the S material, and it was estimated that part of the sulfur in the S material was replaced with selenium. Table 3 also shows the element ratios of sulfur and selenium with respect to the total amount of carbon, hydrogen, nitrogen and chalcogen in Comparative Examples 6 and 7.

(Evaluation results of electrochemical characteristics)
FIG. 3 is a graph showing the charge / discharge waveforms of Examples 1 and 2 and Comparative Example 1 that are all PAN-based. In the PANSSe obtained by selenizing the S material PANS, the discharge voltage VD0.5 increased and the charge voltage VC0.5 decreased compared to the PANS. Moreover, in PANSe which is Se material, compared with PANS, although the discharge voltage VD0.5 fell, since the charge voltage VC0.5 also fell, the charge / discharge voltage difference (V) became small. The charge / discharge voltage difference (V) here refers to a charge / discharge voltage difference at a normalized capacity of 0.5, that is, a charge / discharge depth (SOC) of 0.5.

  Table 4 shows the evaluation results of electrochemical characteristics such as discharge capacity, energy efficiency, discharge voltage, charge / discharge voltage difference, and voltage loss. Table 4 also shows the theoretical capacity when selenium and sulfur are added alone. From Table 4, it was found that the discharge capacity was larger than the theoretical capacity expected from the contents of selenium and sulfur. Further, the capacitor component was confirmed by cyclic voltammetry (hereinafter also referred to as CV) described later. From this, it was inferred that capacitor components were superimposed when the weight ratio of selenium was 15% by weight or more. FIG. 4 is a graph showing the CV results of Example 1 and Comparative Example 1. The PANSe CV of Example 1 was measured in the region of 2.1V to 3V after charging up to 3V, and measured in the region of 0.7V to 1.7V after discharging to 0.7V. In the CNS of the PANS of Comparative Example 1, measurement was performed in the region of 2.2V to 3V after charging up to 3V, and measurement was performed in the region of 1V to 2V after discharging up to 1V. From FIG. 4, it was found that in both Example 1 and Comparative Example 1, the capacitance increased in the scan in the low voltage range as compared to the scan in the high voltage range. From this, it was speculated that the capacitance generated by oxidation-reduction was superimposed on the battery capacity as a capacitor component, and the capacity was significantly increased. Here, since the capacity is considered to increase due to the superposition of the capacitor component of the polycyclic aromatic moiety generated by redox of the chalcogen substituent, it is preferable that many chalcogen substituents can be bonded, and in the case of a polycyclic aromatic structure It was speculated that a polyacene structure with many edges was suitable for this. Moreover, it was speculated that the polyacene structure does not need to be an aromatic ring composed of only carbon, and may be those of Examples 3 to 6 in which the aromatic rings are connected by an aromatic heterocycle.

  Moreover, since Examples 1-6 which are Se material and SSe material are higher energy efficiency than Comparative Examples 1-5 which are S material and SeS material in Table 4, the chalcogen couple | bonded with a carbon material is selenium alone. However, it turned out that both selenium and sulfur may be used. As shown in Table 2, in Examples 1 and 3, selenium was introduced by heating and baking. However, since the reactivity of selenium was low, the residual amount of hydrogen was large. For this reason, the selenium concentration was lower than those of Examples 2, 4, 5, and 6, and it was assumed that this contributed to a decrease in discharge capacity. However, it was speculated that this is not an essential problem because it can be prevented by increasing the concentration of selenium during the reaction. Moreover, in Example 3 and Example 6, since the discharge voltage was low, it was guessed that it was effective also as a negative electrode material which is hard to produce the dendrite of Li by combining with a high voltage positive electrode material, for example. Moreover, it was found that the SSe material can increase the charge / discharge energy efficiency and reduce the charge / discharge potential difference and the voltage loss while suppressing the decrease in capacity as compared with the Se material. It was found that with the SSe material, the discharge voltage was rather high as in Example 2. Therefore, it was considered as a promising electrode material as a positive electrode material.

  When compared with those having the same carbon skeleton, it was found that the Se material and the SSe material showed better characteristics in terms of energy efficiency, charge / discharge voltage difference, and voltage loss than the S material. However, in Comparative Examples 6 and 7 in which the weight ratio of selenium was 15% or less and sulfur was not contained, the capacity was extremely low. In Comparative Example 2 in which sulfur was contained although the selenium concentration was low, it was found that although the capacity was large, the energy efficiency was rather lower than that in Comparative Example 1. Thus, it was found that the selenium concentration is preferably at least 15% by weight. Regarding the discharge capacity per active material weight, the capacity of the S material was higher. However, since the specific gravity of sulfur is 2 while the specific gravity of selenium is 4.8, it is presumed that the capacity per volume regarded as important in the battery is inferior. As a method for introducing selenium, it has been found that high concentration is difficult by heating and baking. In particular, even when a low molecular weight polycyclic aromatic compound is directly heated and baked with selenium, the selenium concentration is as low as 2 at% or less as in Comparative Examples 6 and 7. This is presumed to be due to the low reactivity of selenium and the volatility of the raw material. As a method for producing the electrode material of the present invention from such a relatively low molecular weight polycyclic aromatic compound, after preparing a composite material with sulfur in advance, a part or all of the sulfur is replaced with selenium. It turned out that the chalcogen carbon composite storage battery-like electrode material preparation method including a process is suitable. By performing this, it was speculated that a high-concentration selenium composite material could be produced from the raw material aromatic compounds of Comparative Examples 6 and 7 and anthracene having a lower molecular weight than that as in Example 5.

  FIG. 5 is a graph showing the relationship between the temperature and discharge capacity in Example 1 and Comparative Example 1. Here, the state of capacity reduction when the discharge capacity at 25 ° C. is set to 100 is shown. From FIG. 5, in Comparative Example 1 consisting of only sulfur, the capacity is reduced at −15 ° C. at 0.5 mA and even at a low current of 0.1 mA, whereas a significant decrease in capacity at −30 ° C. is observed. In Example 1, a high capacity of 50% or more was maintained even at −30 ° C. at 0.1 mA. Although there is a strong demand for batteries that can be charged and discharged at −30 ° C., it has been difficult to achieve with conventional batteries. It can be said that the present invention is an electrode material exhibiting breakthrough performance that can be charged and discharged at −30 ° C.

  As described above, in Examples 1 to 6, the new phenomenon of superposition of capacitor components associated with oxidation / reduction shows a capacity higher than the theoretical capacity expected from the chalcogen content, and as an effect of selenization, It was found that high energy efficiency, low charge / discharge voltage difference, low voltage loss, and low temperature characteristics can be realized.

10 Evaluation Cell, 12 Cylindrical Base, 14 Cavity, 16 Negative Electrode, 18 Separator, 20 Positive Electrode, 22 Ring, 24 Column, 25 Pressure Bolt, 25a Through Hole, 26 Lid, 26a Opening, 27 Insulating Resin Ring, 28 Packing, 29 Insulation ring.

Claims (6)

A chalcogen compound having a carbon skeleton and a chalcogen containing at least selenium and having a weight ratio of selenium to the total amount of carbon, hydrogen, nitrogen and chalcogen of 15% or more is used as an electrode active material ,
The chalcogen compound has a polyacene structure in which pyridine rings having chalcogen bonded to the outer periphery are arranged in a row, or a structure in which an aromatic ring having chalcogen bonded to the outer periphery is connected by a heterocycle containing chalcogen,
Power storage device.   The electricity storage device according to claim 1, wherein the chalcogen compound further contains sulfur as a chalcogen. The carbon skeleton has an aromatic ring structure;
In the oxidized state, the chalcogen forms a dichalcogenide bond in which one of two bonds is bonded to the aromatic ring structure and the other is a dimer with another chalcogen element, or two bonds are bonded. Both are couple | bonded with the aromatic ring structure, The electrical storage device of Claim 1 or 2. A manufacturing method for manufacturing an electrode active material used for an electrode of an electricity storage device,
A selenization step in which sulfur of a sulfur compound having a bond between a carbon skeleton and sulfur is substituted with selenium,
A method for producing an electrode active material comprising:   The method for producing an electrode active material according to claim 4, wherein in the selenization step, the sulfur compound and selenium are mixed and heated to replace sulfur with selenium. Before the selenization step, a sulfurization step of synthesizing the sulfur compound by mixing and heating a compound capable of forming the carbon skeleton and sulfur,
The manufacturing method of the electrode active material of Claim 4 or 5 containing this.

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