JP2009093943A - Negative active material for secondary battery and secondary battery using this - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative active material for a secondary battery producing no dendrite in charge and causing no damage in charge/discharge; and to provide a secondary battery using it. <P>SOLUTION: The secondary battery is equipped with a negative electrode 4 holding a negative active material 4d for the secondary battery containing a prescribed amount of a metal element having the standard electrode potential lower than gallium in metal containing the prescribed amount of each of tin and gallium, a positive electrode 2, and an ion conductive electrolyte arranged between the negative electrode 4 and the positive electrode 2. The metal element diffuses into the electrolyte as ions of the metal element during discharge, and the ions of the metal element return again to the metal element on the surface of the negative active material during charge, and the metal element diffuses into the negative active material. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a negative electrode active material for a secondary battery and a secondary battery using the same.

  In recent years, lithium secondary batteries have attracted attention as secondary batteries. This is because material specificities such as the specific gravity of lithium (Li) being the smallest among metals and the standard electrode potential being a negative potential showing the largest value of minus 3.04 V have been noticed. However, when the lithium secondary battery is repeatedly charged and discharged, lithium dendrite grows on the negative electrode, causing problems such as breakage or short-circuiting of the separator or reduction in capacity.

  Therefore, various proposals have been made to solve these problems.

  For example, Patent Document 1 discloses at least two types including a cathode, an anode containing a carbon material having a crystallinity> 0.8, a first solvent having a high dielectric constant, and a second solvent having a low viscosity. A lithium secondary battery comprising a mixture of an aprotic organic solvent and an electrolyte comprising a lithium salt, wherein the electrolyte contains at least one unsaturated bond and forms a passivation layer to form a passivation layer Further disclosed is a lithium secondary battery further comprising a soluble compound of the same type as at least one of the solvents, which can be reduced at the anode at a potential higher by 1 V than that of the solvent.

  Patent Document 2 includes an aprotic non-aqueous electrolyte, a positive electrode and a negative electrode that are in effective contact with the electrolyte, the positive electrode is made of a lithium intercalation compound, and the negative electrode is carbon. -A lithium secondary battery comprising a carbon composite material is disclosed.

  Patent Document 3 discloses at least two kinds of materials including a cathode, an anode containing a carbon material having a crystallinity> 0.8, a first solvent having a high dielectric constant, and a second solvent having a low viscosity. A lithium secondary battery comprising a mixture of an aprotic organic solvent and an electrolyte comprising a lithium salt, wherein the electrolyte contains at least one unsaturated bond and forms a passivation layer to form a passivation layer Further disclosed is a lithium secondary battery further comprising a soluble compound of the same type as at least one of the solvents, which can be reduced at the anode at a potential higher by 1 V than that of the solvent.

  Moreover, in patent document 4, it produced by the liquid quenching method for the purpose of suppressing the fall of the charge / discharge cycle characteristic based on the reaction with the electrolyte solution of deposited lithium and the growth of dendrite, and improving a charge / discharge cycle characteristic. Amorphous metals (aluminum (Al), indium (In), gallium (Ga), bismuth (Bi), boron (B), silicon (Si), lead (Pb), tin (Sn), silver (Ag), A negative electrode having a structure in which a gold (Au) plate is sandwiched between two lithium metal plates, an electrolyte is put between them, and electrochemically alloyed in the presence of the electrolyte, and lithium A secondary battery is disclosed.

  Patent Document 5 discloses a Li-X alloy (for the purpose of suppressing dendrite growth in the charging process, improving charge / discharge characteristics, and improving mass productivity of a tape-shaped molded body. X is at least one selected from the group consisting of Al, In, Sn, Ga, and zinc (Zn).) The components are adjusted so that the weight ratio of X is 0.1 to 30% by weight, and then cast. , A negative electrode active material for a lithium secondary battery, which is extruded and finally punched.

  Patent Document 6 discloses a negative electrode active material made of a solid solution alloy in which a small amount of metal (Ga or Ga—In alloy) that is liquid at room temperature is fixed to Sn for the purpose of improving cycle life characteristics. In addition, a negative electrode including the negative electrode and a lithium secondary battery using the negative electrode are disclosed.

  However, the techniques disclosed in Patent Documents 1 to 6 have the following problems.

  That is, if it is a negative electrode as described in patent documents 1 to 3, although generation of Li dendrite can be prevented, a carbon electrode having a layered structure is used for the negative electrode. Volume change occurs. The volume change that occurs in the carbon electrode is due to the insertion and desorption of Li ions that occur in the layered carbon electrode during the charge-discharge process. Moreover, peeling of the carbon electrode occurs due to the volume change occurring in the carbon electrode. In addition, the insertion and desorption of Li ions cause significant expansion and contraction of the carbon electrode, so that the mechanical integrity as a negative electrode is relaxed. As a result, the impedance of the negative electrode also increases, causing a gradual decrease in the capacity of the lithium secondary battery. The current lithium secondary battery is charged and discharged about 500 times at a discharge depth of 100%, and the capacity storage rate is about 80%.

  Moreover, since the structure of the negative electrode described in Patent Document 4 does not exhibit a crystal structure of an amorphous metal plate sandwiched between two lithium metal plates, the electrochemical alloying reaction of lithium during charging is accelerated. However, since the amorphous metal plate is also solid, the electrodeposition rate of metallic lithium on the solid surface is faster than the diffusion rate of Li atoms in the solid, and the effect of suppressing the formation of Li dendrite during charging Is not enough.

  Further, the negative electrode active material for a lithium secondary battery described in Patent Document 5 is solid when repeated charge / discharge, although generation of dendrites during charging is somewhat suppressed as compared with the case of using conventional pure lithium. The grain boundary part of the negative electrode active material is preferentially corroded, the negative electrode active material is lost, and the performance deteriorates.

Moreover, since the negative electrode active material for lithium secondary batteries described in Patent Document 6 is a solid solution alloy, the electrodeposition rate of metallic lithium on the solid surface is faster than the diffusion rate of Li atoms in the solid, and charging is performed. The effect of suppressing the formation of Li dendrite at the time is not sufficient. Moreover, in order to use as an active material for constituting a negative electrode, it is complicated that the alloy must be pulverized after being manufactured.
JP-A-8-45545 Special table 2003-534636 gazette JP 2004-31366 A JP-A 63-13267 JP-A-4-253159 JP 2007-214127 A

  The objective of this invention is providing the secondary battery using the negative electrode active material for secondary batteries which does not produce | generate a dendrite at the time of charge, and does not produce damage at the time of charging / discharging.

The invention according to claim 1 is at least one selected from the group consisting of a metal containing X% tin (meaning mass%, hereinafter the same), Y% gallium and a metal element whose standard electrode potential is lower than gallium. A negative electrode active material for a secondary battery having a seed metal element, wherein the metal satisfies the following formulas (1) to (3), and the standard electrode potential is selected from the group consisting of metal elements lower than gallium The total amount of the at least one metal element is 38% or less (excluding 0%) based on the metal, and is a secondary battery negative electrode active material.
X ≦ 12.5 (1)
87.5 ≦ Y ≦ 100 (2)
Y = 100−X (3)

  According to a second aspect of the present invention, at least one metal element selected from the group consisting of metal elements whose standard electrode potential is lower than that of gallium is at least one of aluminum, zinc, and lithium. The negative electrode active material for secondary batteries described in 1.

  The invention according to claim 3 is a negative electrode in which the negative electrode active material for a secondary battery according to claim 1 or 2 is housed and held, a positive electrode, and an ion conductive electrolyte solution disposed between the negative electrode and the positive electrode. The at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than that of gallium in the negative electrode active material for secondary batteries is a secondary battery comprising: It is configured to diffuse into the electrolyte as ions, and during charging, the ions of the metal element return to the metal element again on the surface of the negative electrode active material for the secondary battery and diffuse into the negative electrode active material for the secondary battery. It is the secondary battery characterized by being made.

  According to a fourth aspect of the present invention, the ion conductive electrolyte is a metal ion conductive electrolyte, and the metal ions in the metal ion conductive electrolyte are standards in the negative electrode active material for secondary batteries. 4. The secondary battery according to claim 3, wherein the secondary battery corresponds to at least one metal element selected from the group consisting of metal elements having a lower electrode potential than gallium.

The negative electrode active material for a secondary battery according to the present invention is selected from the group consisting of a metal containing X% tin (meaning mass%, hereinafter the same), Y% gallium and a metal element whose standard electrode potential is lower than gallium. A negative electrode active material for a secondary battery having at least one metal element, wherein the metal satisfies the following formulas (1) to (3), and the standard electrode potential is lower than that of gallium. The total amount of at least one metal element selected from the group is 38% or less (excluding 0%) based on the metal.
X ≦ 12.5 (1)
87.5 ≦ Y ≦ 100 (2)
Y = 100−X (3)

  The secondary battery according to the present invention is disposed between a negative electrode (details will be described later), a positive electrode (details will be described later) in which the negative electrode active material for a secondary battery is accommodated and held, and between the negative electrode and the positive electrode. An ion conductive electrolyte solution (details will be described later), at least selected from the group consisting of metal elements having a standard electrode potential lower than gallium in the negative electrode active material for the secondary battery One kind of metal element diffuses into the electrolyte as ions of the metal element during discharge, and the ions of the metal element return to the metal element again on the surface of the negative electrode active material for the secondary battery during charging. It is comprised so that it may diffuse in the negative electrode active material for secondary batteries.

Since it is the above structures, this invention has the following effects.
1) Since the negative electrode active material for a secondary battery itself exhibits a low viscosity state as a whole, at least one kind selected from the group consisting of metal elements whose standard electrode potential constituting the negative electrode active material is lower than gallium Metal elements can diffuse smoothly into the electrolyte as ions during discharge. In addition, since the negative electrode active material itself exhibits a low viscosity state as a whole, the ions move to the negative electrode active material side during charging and are electrodeposited as metal on the surface of the negative electrode active material. It can quickly diffuse into the material and return to the metal element. Therefore, no dendrite is generated during charging.
2) The negative electrode active material for secondary batteries is not solid in the first place, and has a low viscosity as a whole. This is caused by the insertion and desorption of ions due to repeated charge and discharge like a layered carbon electrode. The electrode is not damaged by expansion and contraction. Moreover, the negative electrode active material is not lost due to preferential corrosion of the grain boundary portion due to repeated charge and discharge as in the case of solid metal, and the performance is not deteriorated. Thus, since the negative electrode active material is not damaged during charging and discharging, the capacity of the secondary battery is not gradually reduced.

  Hereinafter, embodiments of the present invention will be described in more detail.

(Negative electrode active material for secondary battery according to the present invention and configuration of secondary battery using the same)
The negative electrode active material for a secondary battery according to the present invention is selected from the group consisting of a metal containing X% tin (meaning mass%, hereinafter the same), Y% gallium and a metal element whose standard electrode potential is lower than gallium. A negative electrode active material for a secondary battery having at least one metal element, wherein the metal satisfies the following formulas (1) to (3), and the standard electrode potential is lower than that of gallium. The total amount of at least one metal element selected from the group is 38% or less (excluding 0%) based on the metal.
X ≦ 12.5 (1)
87.5 ≦ Y ≦ 100 (2)
Y = 100−X (3)

  The secondary battery according to the present invention is disposed between a negative electrode (details will be described later), a positive electrode (details will be described later) in which the negative electrode active material for a secondary battery is accommodated and held, and between the negative electrode and the positive electrode. An ion conductive electrolyte solution (details will be described later), at least selected from the group consisting of metal elements having a standard electrode potential lower than gallium in the negative electrode active material for the secondary battery One kind of metal element diffuses into the electrolyte as ions of the metal element during discharge, and the ions of the metal element return to the metal element again on the surface of the negative electrode active material for the secondary battery during charging. It is configured to diffuse into the negative electrode active material for a secondary battery.

Since it is the above structures, this invention has the following effects.
1) Since the negative electrode active material for a secondary battery itself exhibits a low viscosity state as a whole, the standard electrode potential constituting the negative electrode active material for the secondary battery was selected from the group consisting of metal elements lower than gallium. At least one metal element can smoothly diffuse into the electrolyte as ions during discharge. In addition, since the secondary battery negative electrode active material itself exhibits a low viscosity state as a whole, during charging, the ions move to the secondary battery negative electrode active material side, and the secondary battery negative electrode active material At the same time as electrodeposition as metal on the surface, it can quickly diffuse again into the negative electrode active material for secondary battery and return to the metal element. Therefore, no dendrite is generated during charging.
2) The negative electrode active material for secondary batteries is not solid in the first place, and has a low viscosity as a whole. This is caused by the insertion and desorption of ions due to repeated charge and discharge like a layered carbon electrode. The electrode is not damaged by expansion and contraction. Moreover, the negative electrode active material for a secondary battery is not lost due to preferential corrosion of the grain boundary portion due to repeated charge and discharge as in the case of a solid metal, and the performance is not deteriorated. Thus, since the negative electrode active material for secondary batteries is not damaged during charging and discharging, the capacity of the secondary battery is not gradually reduced.

  Hereinafter, the reason for the above configuration will be described in detail.

The present inventor conducted earnest research on how to realize a negative electrode active material for a secondary battery that does not generate dendrites during charging and that does not cause damage during charging and discharging, and a secondary battery using the same. . As a result, it has been common knowledge in the art to use so-called solid materials such as solid metal and layered carbon electrodes as the negative electrode for secondary batteries, but viscosity that cannot be conceived by those skilled in the art. The negative electrode active material for secondary batteries in a low state was found, and by using this, the above object could be achieved. The following two points are considered to be the main points that have achieved the above objective.
1) If there is a problem with a solid-state negative electrode for a secondary battery, it was thought that it could be solved at once by using a material having a low viscosity. Then, in search of a negative electrode active material for a secondary battery that exhibits a low-viscosity state including a metal element that is likely to be reciprocally and smoothly reciprocated between the inside of the negative electrode and the electrolyte during charging and discharging, It is that the negative electrode active material for secondary batteries like a structure was discovered.
2) As a result of assembling as a secondary battery using a negative electrode active material for a secondary battery having the above-described configuration and conducting a basic experiment, it showed predetermined voltage-current characteristics. It was proved that the elements can smoothly diffuse into the electrolyte as ions during discharge. Further, since no dendrite was generated during charging, the ions moved to the negative electrode active material side for the secondary battery during charging, and were electrodeposited as metal on the surface of the negative electrode active material for the secondary battery. It has been proved that it can quickly diffuse into the negative electrode active material for batteries and return to the metal element again. In addition, since the negative electrode active material for the secondary battery is not damaged due to repeated charge and discharge, the negative electrode active material for the secondary battery exhibits a low viscosity state as expected. Even if there is, it was proved that it can be transformed freely.

  The present invention is described in detail below.

A metal containing Sn (standard electrode potential: −0.1375 V) X% (meaning mass%, the same applies hereinafter) and Ga (standard electrode potential: −0.56 V) Y%, and the standard electrode potential is lower than gallium A negative electrode active material for a secondary battery having at least one metal element selected from the group consisting of metal elements, wherein the metal satisfies the following formulas (1) to (3), and the standard electrode potential: Wherein the total amount of at least one metal element selected from the group consisting of metal elements lower than gallium is 38% or less (excluding 0%) based on the metal, It exhibits a low viscosity state.
X ≦ 12.5 (1)
87.5 ≦ Y ≦ 100 (2)
Y = 100−X (3)

  Further, at least one metal element selected from the group consisting of metal elements whose standard electrode potential is lower than Ga is Al, Zn, Li, magnesium (Mg), Si, Ti, lanthanum (La), cerium (Ce). ) Is available. Preferably, at least one of Al, Zn, and Li is used. These metal elements can reversibly reciprocate between the negative electrode and the electrolyte during charge and discharge, and smoothly diffuse into the electrolyte as ions during discharge. It moves to the material side, and is electrodeposited as a metal on the surface of the negative electrode active material for secondary battery. At the same time, it quickly diffuses into the negative electrode active material for secondary battery and returns to the metal element again.

Next, the discharge / charge reaction on the negative electrode side when the negative electrode active material for secondary battery (for example, Sn-Ga-Li, Sn-Ga-Al) is used for the secondary battery is represented by the following formulas (4) to (4) to Shown in (7).
Discharge reaction Sn-Ga-Li → (Sn-Ga) + Li ⁺ + e ⁻ (4)
Charging reaction (Sn—Ga) + Li ⁺ + e ⁻ → Sn—Ga—Li (5)
As shown in the formula (4), Li which is lower than Ga in the secondary battery negative electrode active material (Sn—Ga—Li) is oxidized at the time of discharging, and is eluted and diffused into the electrolyte as ions. Further, as shown in the equation (5), during charging, Li ions in the electrolytic solution move to the secondary battery negative electrode active material side and are reduced on the surface of the secondary battery negative electrode active material, so that the secondary battery negative electrode active material is activated. It quickly diffuses into the material, becomes Sn-Ga-Li again, and Li metal does not generate dendrites on the surface of the negative electrode active material for secondary batteries.
Discharge reaction Sn-Ga-Al → (Sn -Ga) + Al 3+ + 3e - ···
(6)
Charging reaction (Sn—Ga) + Al ³⁺ + 3e ⁻ → Sn—Ga—Al
(7)
Usually, since the surface of Al is covered with an oxide film, even if it is used as a negative electrode, it does not elute smoothly into the electrolyte as ions during discharge. Further, since there is a concern that Al metal is electrodeposited and dendrite is generated as in the case where Li of the prior art is used for the negative electrode at the time of charging, it has not been generally used. However, when the negative electrode active material (Sn—Ga—Al) for secondary batteries of the present invention is used, the above concerns are eliminated, and the negative electrode active material (Sn—Ga—Li) for secondary batteries of the present invention is used. As in the case of the discharge, a good discharge / charge reaction is performed. That is, as shown in the formula (6), Al that is lower than Ga in the secondary battery negative electrode active material (Sn—Ga—Al) is oxidized during the discharge, and is eluted and diffused into the electrolyte as ions. . In addition, as shown in the equation (7), during charging, the Al ions in the electrolyte move to the secondary battery negative electrode active material side and are reduced on the surface of the secondary battery negative electrode active material, so that the secondary battery negative electrode active material is activated. It quickly diffuses into the material, becomes Sn-Ga-Al again, and Al metal is not electrodeposited on the surface of the negative electrode active material for secondary batteries, and dendrite is not generated.

  Further, when the negative electrode active material for secondary battery (Sn—Ga—Zn) of the present invention is used, similarly to the case of using the negative electrode active material for secondary battery of the present invention (Sn—Ga—Al), The above concerns are eliminated, and a good discharge / charge reaction is performed. Further, the metal element having a standard electrode potential lower than Ga constituting the negative electrode active material for a secondary battery of the present invention does not necessarily contain Al, Zn, Li, etc. alone, and the negative electrode for a secondary battery It is only necessary to satisfy the predetermined amount as the total amount of at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than Ga constituting the active material. Further, if the metal element includes, for example, Al and Zn and the Zn content is small in comparison with the Al content, even if all the Al is used up, The remaining battery level does not become zero and the user is informed that the remaining battery level is very low due to the difference in the generated voltage between Al and Zn, and the current is supplied by Zn only for a predetermined time. It also has a unique effect of being able to continue.

  In addition, the content of tin in the metal containing tin and gallium is limited to 12.5% by mass or less when the tin content exceeds 12.5% by mass, which is the core of the technical idea of the present invention. This is because the negative electrode active material for the secondary battery cannot satisfy the condition that it exhibits a low viscosity state. That is, the object of the present invention, which is to provide a negative electrode active material for a secondary battery that does not generate dendrite during charging and does not cause damage during charging and discharging, cannot be achieved. In addition, the total content of at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than Ga constituting the negative electrode active material for secondary batteries is set to 38% or less in the tin content. In the same way that the limit is provided, the condition that the negative electrode active material for a secondary battery, which forms the core of the technical idea of the present invention, exhibits a low viscosity state is satisfied. This is because it is possible to reciprocate smoothly and smoothly between the electrolytes. Such a negative electrode active material for a secondary battery includes a group consisting of a single element of Ga or a metal containing Sn and Ga at a predetermined blending ratio and a metal element having a standard electrode potential lower than Ga on the basis of the single element of Ga or metal. The composition can be easily produced by adding a predetermined amount of at least one selected metal element and stirring and mixing at about 30 ° C to about 100 ° C.

  The negative electrode active material for a secondary battery is housed and held in a housing portion as described below to form a negative electrode. The storage unit is, for example, a cylindrical body made of resin, an ion conductive electrolyte side, an ion exchange membrane connected to one end side of the cylindrical body, and a second end side of the cylindrical body. The current collector is hermetically sealed. Further, the negative electrode active material for a secondary battery is configured to contact the ion exchange membrane and the current collector. The configuration of the negative electrode is an example and is not necessarily limited thereto.

  Next, the positive electrode used for the secondary battery of the present invention will be described below.

For example, a cathode (Pt) plate coated with a positive electrode active material such as MnO ₂ , LiCoO ₂ , V ₂ O ₅ , MoO ₃ , or NiO can be used as the positive electrode. Further, a positive electrode active material such as NiOOH coated on a current collector made of a nickel (Ni) plate can be used as the positive electrode. Furthermore, a non-woven fabric impregnated with an aqueous Ce (SO ₄ ) ₂ solution, an anion exchange membrane provided on one end side of the non-woven fabric on the ion conductive electrolyte side, and provided on the other end side of the non-woven fabric. It is also possible to use a positive electrode composed of a current collector made of a titanium (Ti) plate plated with dripped Pt. The configuration of the positive electrode is just an example and is not necessarily limited thereto.

  Next, the ion conductive electrolyte used for the secondary battery of the present invention will be described below.

As the ion conductive electrolytic solution, an electrolyte dissolved in an organic solvent or water can be used. Various organic solvents such as ethylene carbonate (C ₃ H ₄ O ₃ ), propylene carbonate, butylene carbonate, dimethyl carbonate, and diethyl carbonate can be used. Examples of the electrolyte combined with the organic solvent include LiClO ₄ , LiBF ₄ , LiPF ₆ , LiN (CF ₃ SO ₂ ) ₂ , Al (ClO ₄ ) ₃ , Al (BF ₄ ) ₃ , and Al (PF ₆ ). _3, Zn (ClO ₄ ) ₂ , Zn (BF ₄ ) ₂ , Zn (PF ₆ ) ₂ can be used. In addition, as the electrolyte combined with water, for example, (NH ₄ ) ₂ SO ₄ , KOH, or the like can be used. Also, for example, when at least one metal element selected from the group consisting of metal elements whose standard electrode potential in the negative electrode active material for secondary batteries is lower than gallium is Li, as an ion conductive electrolyte, It is preferable to use a metal ion conductive electrolyte solution in which LiClO ₄ is dissolved in C ₃ H ₄ O ₃ . When Al or Zn is used for at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than that of gallium in the negative electrode active material for secondary batteries, the ionic conductivity is the same as in the case of Li. It is preferable to use an electrolyte for containing a corresponding metal ion in the electrolytic solution.

Moreover, what is called a so-called separator is constituted by impregnating the ion conductive electrolyte into a non-woven fabric or absorbing it in a polymer (for example, polyethylene oxide, acrylic copolymer, etc.). It arrange | positions between positive electrodes. In addition, for example, when using a non-woven fabric impregnated with an ion conductive electrolyte obtained by dissolving KOH in water as a separator, on the side in contact with the negative electrode active material for secondary battery (for example, containing Zn), It is necessary to provide a film that allows H ⁺ , OH ⁻ , K ⁺ , and ZnO ₂ ²⁻ to pass therethrough but does not pass the negative electrode active material. Moreover, when water as mentioned above is used as a solvent, the safety | security as a secondary battery increases.

Hereinafter, the present invention will be described in detail based on examples. However, the following examples are not intended to limit the present invention, and all modifications made without departing from the spirit of the preceding and following descriptions are included in the technical scope of the present invention.

  Examples of a negative electrode active material for a secondary battery and a secondary battery using the same according to the present invention will be described below with reference to the drawings.

Example 1
FIG. 1 is a schematic longitudinal sectional view of a secondary battery according to Example 1 of the present invention. In FIG. 1, 1 is a positive electrode outer can, 2 is a positive electrode, 3 is a negative electrode outer can, 4 is a negative electrode, 5 is a separator, and 6 is an insulating packing.

In FIG. 1, the positive electrode 2 has a configuration in which a positive electrode active material (MnO ₂ or LiCoO ₂ ) is applied to a platinum (Pt) plate. Sample No. shown in Table 1 below. The positive electrode active materials used in 1 to 9 are as follows.

Active material for positive electrode used in invention examples (sample Nos. 1, 3, 5): MnO ₂
Active material for positive electrode used in invention examples (sample Nos. 2, 4, 6) ... LiCoO ₂
Active material for positive electrode used in Comparative Examples (Sample Nos. 7, 8, 9): MnO ₂

  In FIG. 1, a negative electrode 4 includes a cylindrical body 4a made of resin, a cation exchange membrane 4b connected to one end side of the cylindrical body 4a, and a current collector 4c connected to the other end side of the cylindrical body 4a and sealed. And a negative electrode active material 4d for a secondary battery of the present invention that exhibits a low-viscosity state housed in the housing portion (see Nos. 1 to 6 in Table 1 above for the detailed composition). Yes. In addition, the negative electrode active material 4d for the secondary battery includes a simple substance of Ga or a metal containing Sn and Ga in a predetermined mixing ratio, and a predetermined amount of Al, Zn, or Li based on the simple substance of Ga or a metal reference, and is about 30 ° C. A composition prepared by stirring and mixing at about 100 ° C. Further, the negative electrode active material 4d for the secondary battery of the present invention is configured to contact the cation exchange membrane 4b and the current collector 4c. Comparative Example No. The negative electrodes used in 7 and 8 are made of Al alone and Zn alone, respectively. Comparative Example No. The negative electrode used in 9 is an alloy of Al and Li. In the present embodiment, an example in which the cation exchange membrane 4b is used as a constituent element of the negative electrode 4 has been described, but may be omitted as appropriate.

In FIG. 1, the separator 5 is comprised from the ion conductive electrolyte and the nonwoven fabric impregnated with this ion conductive electrolyte. Sample No. shown in Table 1 above. The ion-conducting electrolyte solution (consisting of an organic solvent and an electrolyte) used in 1 to 9 is as follows, and each electrolyte is 1 g / L (L means liter) with respect to the organic solvent. Was dissolved at 50 ° C.
Organic solvents and electrolytes used in the inventive examples (Sample Nos. 1 and 2)
... C ₃ H ₄ O ₃ , Al (ClO ₄ ) ₃
Organic solvents and electrolytes used in Invention Examples (Sample Nos. 3 and 4)
... C ₃ H ₄ O ₃ , Zn (ClO ₄ ) ₂
Organic solvent and electrolyte used in invention examples (sample Nos. 5 and 6)
... C ₃ H ₄ O ₃ , LiClO ₄
Organic solvent and electrolyte used in Comparative Example (Sample No. 7)
... C ₃ H ₄ O ₃ , Al (ClO ₄ ) ₃
Organic solvent and electrolyte used in Comparative Example (Sample No. 8)
... C ₃ H ₄ O ₃ , Zn (ClO ₄ ) ₂
Organic solvent and electrolyte used in Comparative Example (Sample No. 9)
... C ₃ H ₄ O ₃ , LiClO ₄

Sample No. assembled in the above-described configuration. In the secondary batteries 1 to 9, first, the generated voltage and current were measured. As a result, in the inventive examples (Sample Nos. 1 to 6), a voltage of 1.0 to 1.7 V was generated, and a current of 0.3 to 0.5 mA / cm ² flowed (see Table 1 above). . In the comparative examples (Sample Nos. 7 and 8), a voltage was observed at the start of measurement, but the voltage immediately dropped and measurement was impossible. This is presumably because the oxide film on the negative electrode surface hinders conduction. In the comparative example (Sample No. 9), a voltage of 3.0 V was generated, and a current of 0.5 mA / cm ² flowed (see Table 1 above).

  Next, the sample No. Regarding the secondary batteries 1 to 9, whether or not dendrite was generated on the negative electrode surface during charging (after charging for 5 hours at 4 V) and whether or not the electrodes were damaged during charging and discharging were confirmed. As a result, in the invention examples (sample Nos. 1 to 6) and the comparative examples (sample Nos. 7 and 8), generation of dendrite was not observed, but in the comparative example (sample No. 9), generation of dendrite. (See Table 1 above). Moreover, although damage of the electrode at the time of charging / discharging was not recognized in invention example (sample No. 1-6) and comparative example (sample No. 7, 8), in comparative example (sample No. 9), it was damaged. Was recognized.

(Example 2)
FIG. 2 is a schematic longitudinal sectional view of a secondary battery according to Example 2 of the present invention. In the present embodiment, the same constituent elements as those in the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions are described in detail. In FIG. 2, 7 is a positive electrode, and the positive electrode 7 includes a current collector 7a made of a titanium (Ti) plate plated with Pt, a non-woven fabric 7b impregnated with a Ce (SO ₄ ) ₂ aqueous solution, and an anion exchange membrane 7c. It is composed of The Ce (SO ₄ ) ₂ aqueous solution is obtained by dissolving 2 g / L of the electrolyte Ce (SO ₄ ) ₂ in water. Further, the anion exchange membrane. 7c, SO ₄ ^over can pass but has a structure ^{in which Ce 4+} can not pass through. The configuration of the positive electrode 7 is used for both the inventive examples (Sample Nos. 10 and 11) and the comparative example (Sample No. 12) shown in Table 2 below.

  The negative electrode 4 is the same as that of Example 1 with respect to the inventive examples (sample Nos. 10 and 11) (however, the detailed composition is shown in Table 2 above), but the comparative example (sample No. 12) is Zn. It consists of a simple substance. Also in the present embodiment, as in the first embodiment, the example in which the cation exchange membrane 4b is used as the constituent element of the negative electrode 4 has been described, but may be omitted as appropriate.

Moreover, the separator 5 is comprised similarly to Example 1 from the ion conductive electrolyte and the nonwoven fabric impregnated with this ion conductive electrolyte. However, an aqueous solution of (NH ₄ ) ₂ SO ₄ is used as the ion conductive electrolyte. This (NH ₄ ) ₂ SO ₄ aqueous solution is obtained by dissolving 2 g / L of the electrolyte (NH ₄ ) ₂ SO ₄ in water.

Sample No. assembled in the above-described configuration. In 10 to 12 secondary batteries, first, the generated voltage and current were measured. As a result, in the inventive examples (Sample Nos. 10 and 11), voltages of 2.0 and 2.2 V were generated, respectively, and currents of 0.3 and 0.4 mA / cm ² flowed (see Table 2 above). ). In the comparative example (Sample No. 12), a voltage of 1.8 V was generated, and a current of 0.3 mA / cm ² flowed (see Table 2 above).

  Next, the sample No. About the secondary battery of 10-12, the presence or absence of the generation | occurrence | production of the dendrite to the negative electrode surface at the time of charge (after charging for 5 hours at 2.5V), and the presence or absence of the damage of the electrode at the time of charging / discharging were confirmed. As a result, in the invention examples (samples No. 10 and 11), no dendrite formation was observed, but in the comparative example (sample No. 12), dendrite formation was observed (see Table 2 above). Further, in the inventive examples (Sample Nos. 10 and 11), no damage to the electrodes during charging and discharging was observed, and no damage was observed in the comparative example (Sample No. 12).

(Example 3)
FIG. 3 is a schematic longitudinal sectional view of a secondary battery according to Example 3 of the present invention. In the present embodiment, the same constituent elements as those in the first embodiment are denoted by the same reference numerals, detailed description thereof is omitted, and only different portions are described in detail. In FIG. 3, 8 is a positive electrode, and the positive electrode 8 is a positive electrode in which a positive electrode active material NiOOH is applied to a current collector made of a nickel (Ni) plate. In the invention example (sample No. 13) shown in Table 3 below, the configuration of the positive electrode 8 is used.

  The negative electrode 4 is basically the same as in Example 1 (however, the detailed composition is shown in Table 3 above). However, when a separator 9 as described later is used, a positive electrode is used as a component of the negative electrode 4. The ion exchange membrane 4b is unnecessary.

The separator 9 is composed of a nonwoven fabric 9a impregnated with an ion conductive electrolyte and a membrane 9b having pores. However, 20 mass% KOH aqueous solution is used as the ion conductive electrolyte. The film 9b is provided between the negative electrode 4 and the nonwoven fabric 9a. Moreover, when Zn is contained as the negative electrode active material 4c for the secondary battery as in this embodiment, the film 9b can pass H ⁺ , OH ⁻ , K ⁺ , and ZnO ₂ ²⁻ , but the negative electrode active material. Has a structure that does not pass.

Sample No. assembled in the above-described configuration. In 13 secondary batteries, first, generated voltage and current were measured. As a result, in the inventive example (Sample No. 13), a voltage of 1.5 V was generated, and a current of 0.3 mA / cm ² flowed (see Table 3 above).

  Next, the sample No. For No. 13 secondary battery, the presence or absence of dendrite generation on the negative electrode surface during charging (after charging for 5 hours at 2.5 V) and the presence or absence of electrode damage during charging and discharging were confirmed. As a result, in the invention example (sample No. 13), generation of dendrite was not observed (see Table 3 above). Moreover, in the example of an invention (sample No. 13), the damage of the electrode at the time of charging / discharging was not recognized.

It is a model longitudinal cross-sectional view of the secondary battery of Example 1 of this invention. It is a model longitudinal cross-sectional view of the secondary battery of Example 2 of this invention. It is a model longitudinal cross-sectional view of the secondary battery of Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode outer can 2, 7, 8 Positive electrode 3 Negative electrode outer can 4 Negative electrode 4a Cylindrical body 4b Cation exchange membrane 4c, 7a Current collector 4d Negative electrode active material for secondary batteries 5, 9 Separator 6 Insulation packing 7b, 9a Nonwoven fabric 7c Anion exchange membrane 9b Membrane with pores

Claims (4)

It had a metal containing X% tin (meaning of mass%, the same shall apply hereinafter) and Y% gallium, and at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than that of gallium. A negative electrode active material for a secondary battery, wherein the metal satisfies the following formulas (1) to (3), and the standard electrode potential is at least one metal element selected from the group consisting of metal elements lower than gallium. The total amount is 38% or less (excluding 0%) based on the metal, wherein the negative electrode active material for a secondary battery.
X ≦ 12.5 (1)
87.5 ≦ Y ≦ 100 (2)
Y = 100−X (3)   2. The negative electrode active for secondary battery according to claim 1, wherein at least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than that of gallium is at least one of aluminum, zinc, and lithium. material.   A secondary battery comprising: a negative electrode in which the negative electrode active material for a secondary battery according to claim 1 is housed and held; a positive electrode; and an ion conductive electrolyte disposed between the negative electrode and the positive electrode. At least one metal element selected from the group consisting of metal elements having a standard electrode potential lower than gallium in the negative electrode active material for secondary batteries diffuses into the electrolyte as ions of the metal element during discharge. In addition, the secondary electrode is configured such that, during charging, ions of the metal element return to the metal element again on the surface of the negative electrode active material for the secondary battery and diffuse into the negative electrode active material for the secondary battery. battery.   The ion conductive electrolyte is a metal ion conductive electrolyte, and the metal ions in the metal ion conductive electrolyte are from metal elements whose standard electrode potential in the negative electrode active material for secondary batteries is lower than gallium. The secondary battery according to claim 3, wherein the secondary battery corresponds to at least one metal element selected from the group consisting of:

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