JP5293926B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery including a liquid electrolyte having excellent storage characteristics and safety.

  In recent years, with the development of portable devices such as personal computers and mobile phones, the demand for batteries as power sources has been greatly expanded. In batteries used for such applications, liquid electrolytes (electrolytic solutions) such as organic solvents are widely used as a medium for moving ions. For the purpose of improving safety, secondary batteries using an ionic liquid, which is a room temperature molten salt, as an electrolyte have been studied. Since the ionic liquid does not burn and does not evaporate at room temperature, it can be expected that the possibility of ignition due to liquid leakage is reduced.

As a secondary battery using such an ionic liquid, a secondary battery using Li ions as a conductive cation component is known. One is that using lithium oxide for the positive electrode and carbon or lithium alloy for the negative electrode (for example, Patent Document 1). Further, there are known ones using metal oxides, sulfides and nitrides for the negative electrode, and those in which the negative electrode is 1 V more noble than metal lithium (Patent Documents 2 and 3).
JP-A-4-349365 Japanese Patent Laid-Open No. 10-92467 JP 2001-319688 A

  However, in a secondary battery using an organic solvent-based liquid electrolyte, a protection device and a package for ensuring its safety are indispensable. In the secondary battery using the ionic liquid described in Patent Document 1 as an electrolyte, since the negative electrode is base, the ionic liquid tends to be reduced and cycle characteristics tend to deteriorate. In the batteries described in Patent Documents 2 and 3, since the potential of the negative electrode is relatively high, the reduction of the ionic liquid can be suppressed, but the overall battery potential is lowered.

  In addition, according to the present inventors, in the battery configuration of the conventional secondary battery, since the potential difference is always generated in the material between the positive and negative electrodes, the deterioration of the electrolyte is promoted, and the storage characteristics are increased. Was thought to have declined.

  On the other hand, using sodium ions as the conductive cation component is considered to be more cost effective than using lithium ions, but it cannot be said that an appropriate negative electrode material has been found. Furthermore, the safety at the time of precipitation cannot be solved.

  Therefore, an object of the present invention is to provide a secondary battery using a liquid electrolyte having excellent storage characteristics. Another object of the present invention is to provide a secondary battery using a liquid electrolyte that is further excellent in safety. Furthermore, another object of the present invention is to provide a method for manufacturing a secondary battery using a liquid electrolyte excellent in storage characteristics and safety.

  The present inventors have found that a secondary battery having excellent storage characteristics can be provided by making the active material of the positive electrode and the negative electrode the same compound, and the present invention has been completed. In addition, the present inventors have also found that by using a material having a so-called NASICON structure as an active material as a material for a positive electrode and a negative electrode, a secondary battery using an ionic liquid having excellent storage characteristics and safety as an electrolyte can be provided. It was. The present invention provides the following means based on these findings.

  According to the present invention, there is provided a secondary battery comprising a positive electrode, a negative electrode and a liquid electrolyte, wherein the positive electrode and the negative electrode contain the same active material.

[式（１）中、Ｍは、Ｈ、Ｌｉ、Ｎａ、Ｍｇ、Ａｌ、Ｋ及びＣａから選択されるいずれかを表し、Ｎは、遷移金属、Ａｌ及びＣｕから選択される少なくとも一種を表し、Ｘは、ＳｉＯ₄、ＰＯ_４、ＳＯ_４、ＭｏＯ₄、ＷＯ₄、ＢＯ₄及びＢＯ₃から選択される少なくとも一種のポリアニオンを表し、ａは０〜５、ｂは１〜２、ｃは１〜３を表す。] In the present secondary battery, the above-mentioned secondary battery is also provided in which the same active material contains a substance represented by the following formula (1).

[In formula (1), M represents any one selected from H, Li, Na, Mg, Al, K and Ca, N represents at least one selected from transition metals, Al and Cu, X represents at least one polyanion selected from SiO ₄ , PO ₄ , SO ₄ , MoO ₄ , WO ₄ , BO ₄ and BO ₃ , a is 0 to 5, b is 1 to 2, and c is 1 to 2 3 is represented. ]

  Furthermore, any one of the above secondary batteries in which the same active material has a NASICON structure is also provided.

  Moreover, according to the present invention, the liquid electrolyte contains any ion selected from H, Li, Na, Mg, Al, K, and Ca as a conductive cation component. A battery is also provided, and any one of the above secondary batteries, wherein the same active material contains the same metal as the metal ion constituting the conductive cation component of the liquid electrolyte is also provided.

  Furthermore, according to the present invention, there is also provided the secondary battery according to any one of the above, wherein the liquid electrolyte contains an ionic liquid.

  According to the present invention, there is also provided a method for manufacturing a secondary battery including a positive electrode, a negative electrode, and a liquid electrolyte, the manufacturing method including the positive electrode containing the same active material and an electrode manufacturing step for manufacturing the negative electrode. Provided. Furthermore, the manufacturing process is also a process in which a material having a NASICON structure represented by the above formula (1) is used as an active material for the positive electrode and the negative electrode, respectively. There is also provided any of the above production methods including a secondary battery production step of producing a secondary battery using, as a component, an ionic liquid containing M ions in the formula (1) as a liquid electrolyte.

  In the secondary battery including the positive electrode, the negative electrode, and the liquid electrolyte of the present invention, the positive electrode and the negative electrode can contain the same active material. By adopting a symmetrical electrode configuration in which the positive and negative electrode active materials are the same compound, the electrode potential difference before charging or after discharging can be made zero or in the vicinity thereof. As a result, it is possible to effectively suppress the deterioration of the electrolyte and improve the storage characteristics. Furthermore, in particular, since the electrode active material having a NASICON structure has an appropriate potential that does not reduce an ionic liquid containing the same metal ion as a conductive cation component, a secondary battery using these materials as an electrode and an electrolyte Then, a secondary battery having storage characteristics and safety can be provided.

  Moreover, since the same active material is contained, the volume change at the time of charging / discharging can be canceled, or the volume change of both poles can be estimated easily and the inconvenience based on the difference of the said volume change can be avoided.

  The manufacturing method of the secondary battery of this invention provides a manufacturing method provided with the electrode preparation process which produces the said positive electrode and the said negative electrode containing the same active material. By providing such an electrode manufacturing step, a secondary battery having an electrode potential difference of 0 or near 0 can be obtained, and a secondary battery having excellent storage characteristics can be configured. Moreover, an electrode preparation process can be efficiently and simplified by containing the same active material. In this way, the symmetrical electrode configuration in which the positive and negative electrode active materials are the same compound makes it possible to easily equalize the electrode potential difference before or after charging, thereby effectively suppressing the deterioration of the electrolyte. As a result, the storage characteristics can be improved. Furthermore, in particular, since the electrode active material having a NASICON structure has an appropriate potential that does not reduce an ionic liquid containing the same metal ion as a conductive cation component, a secondary battery using these materials as an electrode and an electrolyte Then, a secondary battery having storage characteristics and safety can be provided.

  Hereinafter, a secondary battery and a manufacturing method thereof, which are embodiments of the present invention, will be sequentially described with reference to the drawings as appropriate. FIG. 1 is a diagram showing an embodiment of a secondary battery of the present invention.

(Secondary battery)
As shown in FIG. 1, the secondary battery 2 of the present invention can include a positive electrode 4, a negative electrode 8, and a liquid electrolyte 12. Although not particularly illustrated, the positive electrode 4 and the negative electrode 8 are each electrically connected to a current collector.

(Positive electrode)
In the secondary battery 2 of the present invention, the positive electrode 4 can similarly adopt an aspect that can be adopted in a secondary battery including a conventionally known liquid electrolyte. The shape, size, and the like of the electrode are not particularly limited, and can be appropriately set depending on the form of the secondary battery 2 and the manufacturing method.

  The positive electrode 4 can contain a positive electrode active material. The positive electrode active material that can be used for the secondary battery 2 can be the same active material as the negative electrode active material, as will be described later. As the positive electrode active material, various metal compounds can be used. Specific examples of the positive electrode active material include a lithium phosphate compound and a sodium phosphate compound.

Moreover, the positive electrode active material represented by following formula (1) can also be included.

In the formula (1), M is any one selected from H, Li, Na, Mg, Al, K, and Ca, and preferably any one selected from Li, Na, and Mg. In the formula (1), X is preferably at least one polyanion selected from SiO ₄ , PO ₄ , SO ₄ , MoO ₄ , WO ₄ , BO ₄ and BO ₃ . More preferred are PO _{4 and} MoO ₄ . Furthermore, in Formula (1), it is preferable that a is 0-5, b is 1-2, and c is 1-3. Moreover, in Formula (1), N is at least 1 type selected from a transition metal, Al, and Cu, and it is preferable that N is at least 1 type selected from Fe, Co, V, and Cu especially.

The substance represented by the formula (1) can take a NASICON structure. Specific examples of such positive electrode active materials include LiFePO ₄ , LiCoPO _4, LiNa ₂ PO ₄ , Li ₃ V ₂ (PO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ₃ , LiVPO ₄ F, and NaVPO ₄ F. Can be mentioned. More preferred are Li ₃ V ₂ (PO ₄ ) ₃ , Na ₃ V ₂ (PO ₄ ) ₃ and LiVPO ₄ F.

  In addition, the positive electrode 4 can contain an electron conduction auxiliary agent and a binder suitably besides a positive electrode active material. Examples of the electron conduction aid include acetylene black, carbon black, graphite, various carbon fibers, and carbon nanotubes. Examples of the binder include polyvinylidene fluoride (PVDF), SBR, polyimide, polytetrafluoroethylene, and the like. The positive electrode 4 can be used in combination of one or more of these various active materials.

(Negative electrode)
Similarly to the positive electrode 4, the negative electrode 8 can similarly adopt an aspect that can be adopted in a secondary battery including a conventionally known liquid electrolyte. The shape, size, and the like of the electrode are not particularly limited, and can be appropriately set depending on the form of the secondary battery 2 and the manufacturing method.

  The negative electrode 8 can contain a negative electrode active material. The negative electrode active material that can be used in the secondary battery 2 can be the same active material as the positive electrode active material already described, as will be described later. Therefore, an active material that can be preferably used as the active material of the positive electrode 4 can be used as the active material of the negative electrode 8 as well. In addition, the negative electrode 8 can contain various electron conduction assistants and binders in addition to the active material, similarly to the positive electrode 4. The negative electrode 8 can be used in combination of one or more of these various active materials.

(Liquid electrolyte)
As the liquid electrolyte 12, a non-aqueous solvent (organic solvent) electrolyte, an ionic liquid, or the like can be used. Nonaqueous solvents for nonaqueous electrolytes include carbonate solvents such as ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), and propylene carbonate (PC), γ-butyrolactone, tetrahydrofuran, acetonitrile, and the like. These single solvents or mixed solvents can be suitably used. Examples of the electrolyte used for the non-aqueous solvent electrolyte include lithium complex fluorine compounds such as lithium hexafluorophosphate (LiPF ₆ ) and lithium borofluoride (LiBF ₄ ), sodium hexafluorophosphate (NaPF ₆ ), and borofluoride. Examples thereof include sodium complex fluorine compounds such as lithium halide (NaBF ₄ ), sodium halides such as sodium perchlorate (NaClO ₄ ), sodium bis (oxalato) borate (NaBOB), and the like. It can be used by dissolving in a solvent. In particular, it is preferable to use LiPF ₆ or NaPF _6, which hardly undergoes oxidative decomposition and has high conductivity of the non-aqueous electrolyte.

  Here, the ionic liquid is an ion-binding substance having a low melting point and a liquid at room temperature. The ionic liquid has very low volatility, is flame retardant, and has excellent conductivity and heat resistance.

  Examples of the cation constituting the ionic liquid include N, N′-dialkylimidazolium cation and N-alkylpyridinium cation. In particular, as specific examples of N, N′-dialkylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1,3-dimethylimidazolium cation, 1,3,4-trimethylimidazolium cation, 1-ethyl -3 methyl imidazolium cation (EMI), 1-hexyl-3-methyl imidazolium cation, and 1-methyl 3-octyl imidazolium cation. Among them, 1-ethyl-3 methyl imidazolium cation is preferable. Of the N-alkylpyridinium cations, 1-butylpyridinium cation is particularly desirable. An ionic liquid composed of these cations is excellent in ion conductivity, chemical stability, and electrochemical stability.

The anion constituting the ionic liquid is desirably selected from at least one of BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ CO ₂ ⁻ , and CF ₃ SO ₃ ^−. . Ionic liquids composed of these fluoride anions have high thermal stability and are difficult to decompose even at high temperatures. In particular, a combination of 1-ethyl-3methylimidazolium cation and (CF ₃ SO ₂ ) ₂ N ⁻ is preferable.

As the liquid electrolyte 12, it is preferable to use a combination of an ionic liquid and an electrolyte. The liquid electrolyte 12 preferably contains any ion selected from H, Li, Na, Mg, Al, K, and Ca as the conductive cation component. In particular, by using an ionic liquid containing Na or Li as a conductive cation component as the liquid electrolyte 12, output and storage characteristics can be improved. Furthermore, by using Na as a conductive cation component, it is possible to improve storage characteristics as an ionic liquid using Na and to improve the cost merit of the secondary battery 2. Na also has an advantage in that it does not form a passive film.

  When the liquid electrolyte 12 is used in combination with an ionic liquid and an electrolyte, the electrolyte is preferably contained in an amount of 0.1 mol / l or more and 1.5 mol / l or less based on the total amount thereof. By mixing at this blending ratio, it is possible to enjoy the merit of safety using ionic liquid, the merit of conductivity using conductive cation components such as Na and Li, and the merit related to cost. Preferably, the electrolyte is blended in an amount of 0.3 mol / l to 1.2 mol / l with respect to the total amount.

  In the secondary battery 2 of the present invention, the liquid electrolyte preferably contains an ionic liquid. Since the ionic liquid has non-volatility, flame retardancy, high ionic conductivity, and chemical stability, a secondary battery excellent in safety can be configured. The ionic liquid preferably contains any ion selected from H, Li, Na, Mg, Al, K, and Ca as the conductive cation component. More preferably, an ionic liquid containing the same ion as that constituting the active material of the positive and negative electrodes, that is, an ion of M in formula (1) as a conductive cation component is used as the liquid electrolyte. By doing so, it is possible to easily manufacture a secondary battery that is excellent in storage characteristics and output and has high safety.

(Active material in positive and negative electrodes)
In the secondary battery 2 of the present invention, the positive electrode 4 and the negative electrode 8 can contain the same active material. By making the active material of both electrodes the same compound, the essential electrode potential difference between the two electrodes can be easily made zero or near zero. As a result, the potential difference is made zero or near zero before charging and after discharging. be able to. For this reason, it is possible to suppress deterioration due to electrolysis of the electrolyte caused by the positive / negative bipolar potential difference, and it is possible to dramatically improve long-term storage characteristics.

  Here, the positive electrode 4 and the negative electrode 8 containing the same active material means containing at least one type of the same active material. More preferably, the active materials of the positive electrode 4 and the negative electrode 8 are all the same. In addition, each compounding ratio of the same active material contained in the positive electrode 4 and the negative electrode 8 can also be made the same. Typically, the positive electrode 4 and the negative electrode 8 can be configured to be single and include the same active material.

It is preferable to use the same active material shown by Formula (1) as the same active material in both electrodes. This is because the active material represented by the formula (1) easily constitutes a preferable electrode potential. In particular, when the active material represented by the formula (1) is a NASICON structure material using Li or Na as M, the internal resistance can be effectively reduced. At this time, the active material is a NASICON structure material, and X is more preferably PO ₄ . At this time, the liquid electrolyte preferably contains an ionic liquid. This is because the active material represented by the formula (1) has an appropriate potential (about 1 V with respect to Li) that does not reduce the ionic liquid.

  It is preferable that both the active material of the positive electrode 4 and the active material of the negative electrode 8 contain the same metal (M) as the metal ion constituting the conductive cation component of the liquid electrolyte 12. If it carries out like this, since mutual ion conductivity will improve and taking out of a large current and charging / discharging cycling characteristics will improve, it can be set as the secondary battery 2 which is excellent in a storage characteristic with high output. Further, at this time, when the liquid electrolyte 12 is an ionic liquid and the conductive cation component is Li or Na, higher output can be expected.

  Furthermore, as described above, when the ionic conductor containing Na ions as the conductive cation component is used as the liquid electrolyte 12, it is difficult to realize the conventional Na battery while enjoying the cost merit of Na and the merit as the cation component. The sodium ion secondary battery 2 excellent in safety and storage characteristics can be constructed.

  The battery structure of the secondary battery 2 of the present invention is not particularly limited, and various structures that can be constituted by the electrolyte material or electrode material of the present invention can be adopted. For example, a coin-type battery in which a separator is disposed between a positive electrode active material and a negative electrode active material that are formed into a plate shape and filled with an electrolytic solution, or a positive electrode obtained by applying a positive electrode active material to the surface of a metal foil Various types of batteries such as a cylinder type and a box type using an electrode body obtained by winding or laminating a plate and a negative electrode plate similarly coated with a negative electrode active material on the surface of a metal foil via a separator be able to.

(Method for manufacturing secondary battery)
The manufacturing method of the secondary battery of this invention can be equipped with the electrode preparation process which produces the said positive electrode and the said negative electrode containing the same active material. Here, for the configurations of the positive electrode 4 and the negative electrode 8, the active material used for each, and the liquid electrolyte 12, these various embodiments in the secondary battery 2 of the present invention described above can be applied as they are.

  In the method for manufacturing the secondary battery 2, the same active material is applied to the positive electrode 4 and the negative electrode 8. In this way, the manufacturing process can be simplified and the storage characteristics of the secondary battery 2 can be improved.

  In the case where the volumes of the positive electrode 4 and the negative electrode 8 are the same, the volume changes at the time of discharging and charging are synchronized, so that such volume changes can always be canceled.

  The manufacturing method can further include a secondary battery manufacturing step using an ionic liquid containing M ions in the formula (1) as the conductive cation component. By doing so, it is possible to easily manufacture a secondary battery that is excellent in storage characteristics and output and has high safety.

  Hereinafter, the present invention will be described with reference to examples. The following examples are provided to illustrate the present invention and are not intended to limit the present invention.

In this example, secondary batteries having various electrode configurations were produced. Table 1 shows the electrode configuration of the fabricated secondary battery.

The electrode active material NVP (Na ₃ V ₂ (PO ₄ ) ₃ ), which is a NASICON structure material, is baked at 900 ° C. for 20 hours in an argon atmosphere containing 5% of 3NaH ₂ PO ₄ and V ₂ O _3. It was made by carrying out twice. The produced ceramic powder was subjected to X-ray diffraction, and a peak based on a specific crystal structure was confirmed. Another electrode active material, LNVP (Li ₃ V ₂ (PO ₄ ) ₃ ), is composed of 3LiH ₂ PO ₄ and V ₂ O ₃ in 5% hydrogen at 900 ° C. for 20 hours under an argon atmosphere. Firing was carried out twice to produce. The produced ceramic powder was subjected to X-ray diffraction, and a peak based on a specific crystal structure was confirmed.

Further, an LVPF (LiVPO ₄ F) having a triclinic system and having a skeleton structure in which a PO ₄ tetrahedron and a VO ₄ F ₂ octahedron are combined was manufactured by the following method. That is, V ₂ O ₅ and NH ₄ PO ₄ were fired by a carbothermal method at 700 ° C. for 4 hours in an argon atmosphere, and the obtained VPO ₄ and LiF were again fired at 700 ° C. for 1 hour in an argon atmosphere. Made. The produced ceramic powder was subjected to X-ray diffraction, and a peak based on a specific crystal structure was confirmed.

  The liquid electrolyte prepared three types of compositions shown in Table 1. Ionic liquids and electrolytes were obtained commercially.

  Using these battery materials, coin cell type secondary batteries were produced according to a conventional method. That is, electrode active material: electron conduction assistant (acetylene black (manufactured by Denki Kagaku Kogyo, 50% press product) was weighed to a weight ratio of 70:25 and mixed for about 15 minutes using an agate mortar. In the sample, polytetrafluoroethylene, which is a binder, was weighed to a weight ratio of 95: 5 and bound using an agate mortar.The resulting electrode material was 10 mm in diameter for the positive electrode and 15 mm in diameter for the negative electrode. Pierced with a cork borer and molded into disk-shaped pellets.

  The procedure for producing the coin cell is as follows. For the positive electrode side part, a titanium wire mesh was cut into a circle having a diameter of 10 mm, spot welded to a spacer, and further spot welded to a coin cell case (R2032). Then, a positive electrode pellet was placed thereon and pressure bonded. For the negative electrode side part, a nickel wire mesh as a current collector was cut into a circle having a diameter of 15 mm, spot welded to a spacer, and a negative electrode pellet was placed thereon and pressure bonded. The coin cell case (R2032) was spot welded with a disc spring and covered with a gasket. The resulting coin cell parts were vacuum-dried at 100 ° C. for about 14 hours using a glass tube oven and moved to an argon-filled glove box (dew point of −85 ° C. or lower). The coin cell was assembled by placing a negative electrode pellet on a negative electrode case, injecting an electrolyte or ionic liquid, placing a polypropylene microporous membrane separator having a diameter of 19 mm thereon, covering a positive electrode part, and sealing with a caulking machine.

In this example, charge / discharge profiles were measured for the four types of coin cell type secondary batteries produced in Example 1. The charge / discharge characteristics are as follows. At 25 ° C., the LVP system is a constant current charge / discharge of 0.1 mA / cm ² in the voltage range of 0-2.5 V, and the NVP system is 0 in the voltage range of 0-1.85 V. Measured by constant current and constant voltage charge and constant current discharge of 1 mA / cm ² . The LVPF system was measured by constant current and constant voltage charging and constant current discharging of 0.1 mA / cm ² in a voltage range of 0 to 2.8V. The results for the batteries 1 to 4 are shown in FIGS. Further, FIG. 6 shows charge / discharge cycle characteristics (25 ° C., 0-1.85 V, 0.2 mA / cm) of the battery 3 (a coin cell made of the positive electrode active material NVP, the electrolyte solution NaBF ₄ / EMIBF ₄ , and the negative electrode active material NVP). ² ) is shown.

  As shown in FIGS. 2 to 5, each coin cell showed good charge / discharge behavior. In addition, good charge / discharge cycle characteristics were exhibited as shown in FIG. From the above, it was found that a secondary battery having excellent storage characteristics can be constructed by using the same compound as the active material for the positive electrode and the negative electrode and using an ionic liquid and / or a non-aqueous solvent electrolyte as the liquid electrolyte. Further, it was found that a secondary battery using an ionic liquid containing Na salt as a liquid electrolyte can be constructed by using a NASICON structure material. Therefore, it has been found that a secondary battery having excellent safety and storage characteristics can be constructed while using Na which is inexpensive and has no fear of energy depletion as a conductive cation component.

It is a figure which shows an example of the battery process of this invention. 2 is a diagram showing a charge / discharge profile of a battery 1 produced in Example 1. FIG. 2 is a diagram showing a charge / discharge profile of a battery 2 produced in Example 1. FIG. 3 is a diagram showing a charge / discharge profile of a battery 3 produced in Example 1. FIG. 3 is a diagram showing a charge / discharge profile of a battery 4 produced in Example 1. FIG. 4 is a diagram showing charge / discharge cycle characteristics of a battery 3 produced in Example 1. FIG.

Explanation of symbols

2 Secondary battery, 4 positive electrode, 8 negative electrode, 12 liquid electrolyte

Claims (8)

A secondary battery comprising a liquid electrolyte containing a positive electrode, a negative electrode and a conductive cation component ,
The positive electrode and the negative electrode contain the same active material having a NASICON structure,
The same active material is a secondary battery selected from Li ₃ V ₂ (PO ₄ ) ₃ and Na ₃ V ₂ (PO ₄ ) ₃ .   The secondary battery according to claim 1, wherein the liquid electrolyte contains any ion selected from Li and Na as a conductive cation component.   The secondary battery according to claim 1, wherein the conductive cation component is an ion of a metal species contained in the same active material. The liquid electrolyte is selected from a cation which is an N, N′-dialkylimidazolium cation, and BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ CO ₂ ⁻ and CF ₃ SO ₃ ^−. The secondary battery in any one of Claims 1-3 containing the anion made. A method for producing a secondary battery comprising a liquid electrolyte containing a positive electrode, a negative electrode and a conductive cation component ,
An electrode manufacturing step for manufacturing the positive electrode and the negative electrode containing the same active material having a NASICON structure;
The manufacturing method in which the same active material is selected from Li ₃ V ₂ (PO ₄ ) ₃ and Na ₃ V ₂ (PO ₄ ) ₃ .   The manufacturing method according to claim 5, wherein the liquid electrolyte contains any ion selected from Li and Na as a conductive cation component.   The method according to claim 5 or 6, wherein the conductive cation component is an ion of a metal species contained in the same active material. The liquid electrolyte is selected from a cation which is an N, N′-dialkylimidazolium cation, and BF ₄ ⁻ , PF ₆ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , CF ₃ CO ₂ ⁻ and CF ₃ SO ₃ ^−. The manufacturing method in any one of Claims 5-7 containing the anion made.

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