JP4110562B2 - battery - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a battery using an alloy as an electrode material.
[0002]
[Prior art]
The battery includes a primary battery such as a Luclanche dry battery, an alkaline dry battery and a lithium primary battery, and a secondary battery such as a lead battery, a nickel cadmium battery, a nickel hydrogen battery, a nickel zinc battery and a lithium ion battery. In the case of a secondary battery in which metal ions such as zinc and lithium are involved in the electrode reaction, the metal may be deposited in the form of a resin (dendritic deposition) on the electrode, thereby reducing the cycle performance. In addition, this dendrite deposition may penetrate the separator and cause an internal short circuit or cause ignition. For example, in lithium secondary batteries, studies have been made to use metallic lithium as a negative electrode active material, but the generation of the dendrites of lithium generated during charging has been a problem.
[0003]
In lithium secondary batteries, the use of lithium alloys has also been studied for the purpose of preventing the dendrite precipitation, but deep charging / discharging, and the repeated charging / discharging causes the lithium alloy to become fine powder or drop off, There was a problem that the battery performance deteriorated. In place of the metals and alloys described above, some batteries have been put into practical use in which a carbonaceous material capable of occluding and releasing lithium ions is used for the negative electrode, thereby extending the life and improving safety. However, in many of these carbonaceous materials, the doping potential of lithium to the carbonaceous material is close to 0V with respect to the potential of metallic lithium. Therefore, when high-rate charging is performed, the doping potential becomes 0V or less. Lithium may be deposited on the top. As a result, internal short-circuiting of the cell may occur or discharge efficiency may be reduced. In addition, such a carbonaceous material has been considerably improved in terms of cycle performance. However, since the energy density of the carbonaceous material as an electrode material is relatively small, the capacity per volume is lowered. become. That is, the carbonaceous material is still insufficient from the viewpoint of high energy density. In addition, the initial charge / discharge efficiency is reduced for those that need to form a film on carbon, and the amount of electricity used to form this film is irreversible, leading to a decrease in capacity for that amount of electricity.
[0004]
On the other hand, as a negative electrode material other than metallic lithium, lithium alloy or carbonaceous material, composite oxide Li containing silicon and lithium_xSi_1-yM_yO_z(Japanese Patent Laid-Open No. 7-230800) and amorphous chalcogen compound M¹M² _pM^Four _q(Japanese Patent Laid-Open No. 7-288123) has been proposed, and some improvement is achieved in terms of high capacity and high energy density.
[0005]
However, the composite oxide as described above has a problem in high rate charge and high rate discharge performance because the electronic conductivity of the material itself is low. In order to solve this problem, addition of a conductive agent has been attempted. However, when a carbon material having a low density is used as the conductive agent, the capacity per volume is reduced. Further, when a high rate charge is performed by adding a conductive agent, current concentration partially occurs and lithium deposition may be observed from the conductive agent. Therefore, the internal short circuit of the cell may be caused or charge / discharge efficiency may be reduced.
[0006]
In addition, since the composite oxide or the like is an oxide itself, it is considered that the reduction reaction of the composite oxide proceeds in parallel with the reaction with lithium. The initial charge / discharge efficiency may be lowered.
[0007]
On the other hand, unlike the above-mentioned silicon simple substance and complex oxide, a negative electrode material such as a non-ferrous metal silicide made of a transition metal is proposed in Japanese Patent Laid-Open No. 7-240201 as a negative electrode material with improved cycle life. . However, although the charge / discharge cycle performance is improved as compared with the metal lithium negative electrode, the battery capacity is only increased by about 12% as compared with natural graphite. As described above, the nonferrous metal silicide made of the transition metal is not necessarily excellent in electrochemical activity capable of efficiently occluding and releasing lithium ions, and therefore the battery capacity cannot be greatly improved. . For example, CeSi is used as a non-ferrous metal silicide made of the transition metal.₂As an example, it has been found that although it has electronic conductivity, it is electrochemically inactive in the charge / discharge potential range. That is, not all of the silicides proposed in the above publication are capable of occluding and releasing lithium, and thus the discharge capacity can be improved even when an electrochemically inert silicide is used. could not.
[0008]
Further, JP 2000-30703 A discloses a composite particle in which another solid phase B is wrapped around a solid phase A as a negative electrode material for a nonaqueous electrolyte secondary battery, and the solid phase A is lithium metal, or One type of element capable of forming an alloy with lithium, or a solid solution or an intermetallic compound containing at least one type of element capable of forming an alloy with lithium, and solid phase B is lithium that forms solid phase A Or a mixed conductor of lithium ions and electrons, which is formed of a solid solution or an intermetallic compound containing at least one element that can be alloyed with lithium, is disclosed in Japanese Patent Application Laid-Open No. 2000-285919. Covers the whole or part of the periphery of the core particle composed of the solid phase A with the solid phase B, the solid phase A containing silicon as a constituent element,RecordSolid phase B is a solid solution of at least one element selected from the group consisting of group 2 elements, transition elements, group 12 and group 13 elements of the periodic table, and group 14 elements excluding carbon and silicon, and metal. A negative electrode material that is an intermetallic compound has been proposed. However, since these electronically conductive coatings are only on the surface, they cannot cope with the electronic isolation of the negative electrode material due to the cracking of the particles that occur when lithium is occluded, resulting in a problem that cycle deterioration is large. there were.
[0009]
[Problems to be solved by the invention]
The negative electrode materials for lithium secondary batteries are summarized above. When lithium metal or lithium alloy is used, it is advantageous in terms of high voltage, high capacity, and high energy density, but there are problems in terms of cycle performance and safety. In the case of using a carbonaceous material, it is advantageous in terms of high voltage and safety, but is insufficient in terms of high capacity and high energy density. Furthermore, when an oxide negative electrode is used, although it seems that it is improved in terms of high capacity and high energy density, it is not satisfactory in terms of high voltage, charge / discharge efficiency, cycle performance and safety.
[0010]
Therefore, in order to obtain an excellent charge / discharge cycle characteristic with high voltage and high energy density and a high safety battery, there is little change in the crystal system and volume change during charge / discharge, and reversible charge / discharge is performed. It has been desired to develop an active material for a battery having high electron conductivity that can be discharged.
[0011]
The present invention has been made in view of the above-described problems, and provides a battery electrode material that has little change in crystal system and volume during charge / discharge, is reversibly chargeable / dischargeable, and has high electron conductivity. It is intended to do. Furthermore, by applying the electrode material for a battery to a battery, the object is to provide a battery exhibiting excellent charge / discharge cycle performance at a high voltage and high energy density and excellent in safety.
[0012]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventors have intensively studied, and surprisingly, a battery having excellent battery characteristics can be obtained by using an alloy having a specific composition as a battery electrode. And found the present invention. That is, the technical configuration and operational effects of the present invention are as follows. However, the action mechanism includes estimation, and the correctness of the action mechanism does not limit the present invention.
[0013]
The present inventionClaimsAs described above, in a battery including a positive electrode, a negative electrode, and an electrolyte, at least one of the positive electrode and the negative electrode includes an alloy, and the alloy includes an alloy of an A phase and a B phase, and the A The phase and the B phase include at least one or more common elements, the A phase is made of a metal, an intermetallic compound, or a solid solution that can be reversibly charged and discharged in the battery, and the B phase is an electron conducting material. The battery is characterized by comprising a metal, an intermetallic compound, or a solid solution that is electrochemically inactive within the battery within a charge / discharge potential range of the battery.
[0014]
Here, “battery charge / discharge potential range” means charging, discharging or leaving as long as the recommended battery is used in the recommended environment described in the catalog, etc. when the battery is sold. Abuse (overcharge, overdischarge, high rate charge / discharge beyond the specified limit, charge / discharge to the battery after the end of the charge / discharge cycle life, charge / discharge under abnormally high temperature, internal short circuit, etc. Use of the generated battery or other abuse) and neglect after the abuse are excluded. That is, an example of a metal “electrochemically inert in the battery in the charge / discharge potential range of the battery” will be described. For example, when copper is used for the negative electrode current collector of a lithium battery, Copper does not elute into the electrolyte during normal use, but the copper may elute slightly depending on the use such as overcharge or after a long and repeated charge / discharge cycle. In such a case, the copper corresponds to the “inert” metal here. Further, the copper has a property of alloying with a very small amount of lithium, but if the alloying is not progressive, the lithium in the alloy can be electrochemically released at least by ordinary charge and discharge. Not a thing. Therefore, in this sense, the copper corresponds to the “inert” metal here. On the other hand, what is not “inactive” means an active substance that is involved in the electrode reaction of the battery. For example, in lithium batteries, lead has the property of reversibly occluding and releasing lithium in large quantities and can be used as a negative electrode material, so the lead does not correspond to the “inert” metal here. .
[0015]
According to such a configuration, the B phase is excellent in electronic conductivity but hardly participates in the charge / discharge reaction. In addition, since the A phase and the B phase contain at least one or more common elements, the A phase and the B phase can form a homogeneous alloy in a relatively wide arbitrary composition range. When such an alloy having two phases is charged and discharged as an electrode, the charge and discharge reaction proceeds reversibly with respect to the A phase, but the B phase is maintained with electronic conductivity. That is, a large matrix having electronic conductivity due to the B phase is formed in the alloy, and the charge / discharge reaction proceeds with respect to the A phase in the matrix. Alternatively, a phenomenon such as dropping is suppressed, an overvoltage associated with the charge / discharge reaction is small, and the electrode material has high capacity and excellent reversibility.
[0016]
The present invention also includes claims.1As described above, the charge / discharge reaction is a reaction in which lithium ions are involved in the electrode reaction, and the phase A is characterized in that lithium can be occluded / released electrochemically.
[0017]
According to such a configuration, the B phase is excellent in electron conductivity but hardly alloyed with lithium. In addition, since the A phase and the B phase contain at least one or more common elements, the A phase and the B layer can form a homogeneous alloy in a relatively wide arbitrary composition range. When lithium is occluded in such an alloy having two phases, although the alloying of lithium proceeds with respect to the A phase, the B phase cannot occlude / release lithium, and the electronic conductivity is reduced. Maintained. That is, a large matrix having electronic conductivity due to the B phase is formed in the alloy, and the A phase in the matrix is alloyed with lithium, whereby lithium is occluded / released. Therefore, the phenomenon of crystal collapse, pulverization or dropping is suppressed, the overvoltage accompanying charge / discharge reaction is small, and the electrode material has a high capacity and excellent reversibility.
[0018]
The present invention also includes claims.2As described above, the charge / discharge reaction is a reaction in which hydroxide ions are involved in the electrode reaction, and the phase A is characterized in that hydrogen can be occluded / released electrochemically.
[0019]
According to such a configuration, the B phase is excellent in electron conductivity, but hardly forms a hydride. In addition, since the A phase and the B phase contain at least one or more common elements, the A phase and the B phasephaseIt is possible to form a homogeneous alloy in a relatively wide arbitrary composition range. When hydrogen is occluded in such an alloy having two phases, the hydrogenation of the A phase proceeds, but the B phase cannot occlude / release hydrogen and is maintained with electronic conductivity. That is, a large matrix having electronic conductivity due to the B phase is formed in the alloy, and the A phase in the matrix is hydrogenated to absorb and release hydrogen. The phenomenon such as the collapse, pulverization, or dropping off is suppressed, the overvoltage associated with the charge / discharge reaction is small, the electrode material has a high capacity and excellent reversibility.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below, but the present invention is not limited to these descriptions.
[0021]
The alloy used in the battery of the present invention is preferably a powder having an average particle size of 0.1 to 100 μm. As a means for obtaining such a powder, a pulverizer, a classifier or the like can be used. For example, a mortar, a ball mill, a sand mill, a vibrating ball mill, a planetary ball mill, a jet mill, a counter jet mill, a swirling air flow type jet mill, a sieve, or the like may be used. For the pulverization, a dry pulverization method may be used, or a wet pulverization method in which an organic solvent such as water or hexane coexists may be used. There is no particular limitation on the classification method, and a sieve, an air classifier, or the like may be used as necessary for both dry and wet processes.
[0022]
When the alloy used for the battery of the present invention is used as a powder, a conductive agent, a binder, a filler, or the like may be added to the electrode mixture.
[0023]
As the conductive agent, any electronic conductive material that does not adversely affect battery performance may be used. Usually, natural graphite (scale-like graphite, scale-like graphite, earth-like graphite, etc.), artificial graphite, carbon black, acetylene black, ketjen black, carbon whisker, carbon fiber and metal (copper, nickel, aluminum, silver, gold, etc.) Conductive materials such as powders, metal fibers, metal deposits, and conductive ceramic materials can be included as one type or a mixture thereof. Of these, graphite, acetylene black, and ketjen black are preferably used in combination. The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight.
[0024]
As binders, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, ethylene-propylene-diene terpolymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluoro rubber, carboxymethylcellulose, methylcellulose (MC), thermoplastic resins such as polyvinyl alcohol (PVA), polymers having rubber elasticity, polysaccharides, and the like can be used as one or a mixture of two or more. Moreover, it is preferable that the binder which has a functional group which reacts with lithium like a polysaccharide performs the process of methylating etc., and deactivates the functional group. The addition amount is preferably 1 to 50% by weight, particularly preferably 2 to 30% by weight.
[0025]
As the filler, any material that does not adversely affect the battery performance may be used. Usually, olefin polymers such as polypropylene and polyethylene, amorphous silica, alumina, zeolite, glass, carbon and the like are used. The amount of filler added is preferably 0 to 30% by weight.
[0026]
As the current collector of the active material, any electronic conductor that does not adversely affect the constructed battery may be used. For example, as a material for the positive electrode current collector, in addition to aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, etc., in order to improve adhesiveness, conductivity, and oxidation resistance, The thing which processed the surface, such as aluminum and copper, with carbon, nickel, titanium, silver, etc. can be used. In addition to copper, stainless steel, nickel, aluminum, titanium, calcined carbon, conductive polymer, conductive glass, Al-Cd alloy, etc., the negative electrode current collector material is adhesive, conductive, and oxidation resistant. For the purpose of improvement, a material obtained by treating the surface of copper or the like with carbon, nickel, titanium, silver or the like can be used. The surface of these materials can be oxidized. As for these shapes, in addition to the foil shape, a film shape, a sheet shape, a net shape, a punched or expanded shape, a lath body, a porous body, a foamed body, a formed body of a fiber group, and the like are used. The thickness is not particularly limited, but a thickness of about 1 to 500 μm is used.
[0027]
As the separator, an insulating thin film having excellent ion permeability and mechanical strength can be used. Sheets, microporous membranes, and nonwoven fabrics made from olefin polymers such as polypropylene and polyethylene, glass fibers, polyvinylidene fluoride, polytetrafluoroethylene, etc. are used because of their organic solvent resistance and hydrophobicity. The pore diameter of the separator is in a range generally used for batteries, for example, 0.01 to 10 μm. Moreover, it is the same also about the thickness, and is a thing of the range generally used for a battery, for example, is 5-300 micrometers.
[0028]
As the electrolyte, for example, an organic electrolyte, a polymer solid electrolyte, an inorganic solid electrolyte, a molten salt, a water-based alkaline electrolyte, or the like can be used.
[0029]
Claim1As described in, when the lithium ion is a reaction involved in the electrode reaction, the A phase capable of electrochemically inserting and extracting lithium includes, for example, lithium, tin, silicon, or an alloy containing these elements Is preferred. The charging / discharging reaction of the alloy containing these elements proceeds at a potential very close to the potential of metallic lithium of about 0.1 V with respect to the potential of metallic lithium. On the other hand, the B phase having electronic conductivity and electrochemically inactive in the charge / discharge potential range is particularly a metal, intermetallic compound or solid solution containing at least one kind of common element with the A phase. Although not limited, in particular, any one of the elements contained in lithium, tin, silicon or alloys thereof contained in the A phase, and the metal elements or metalloid elements of Groups 2 to 16 of the periodic table An alloy that is at least one alloy and that cannot electrochemically occlude and release lithium can be suitably used.
[0030]
For example, an alloy of a solid solution of silicon and a group 3 element and a simple substance of silicon can be given. The solid solution of silicon and a group 3 element is excellent in electron conductivity, but hardly alloyed with lithium. Furthermore, since the solid solution contains silicon, it is possible to form an alloy with an arbitrary composition of silicon alone. When lithium is occluded in an alloy of such a solid solution of silicon and a group 3 element and a simple substance of silicon, although the alloying of lithium proceeds with respect to the simple substance of silicon, the solid solution of silicon and a group 3 element is It remains electronically conductive. That is, a large matrix having an electron conductivity made of a solid solution of silicon and a group 3 element is formed in the alloy, and a single silicon in the matrix occludes / releases lithium so that a charge / discharge reaction proceeds. Therefore, it is considered that the phenomenon of crystal collapse, pulverization, or dropout is suppressed, and the overvoltage associated with insertion and extraction of lithium is reduced. Furthermore, since the charge / discharge reaction in this case proceeds at a potential very close to the potential of metallic lithium of about 0.1 V with respect to the potential of metallic lithium, a high capacity can be obtained as a negative electrode for a lithium battery and reversibility is excellent. It becomes an electrode material.
[0031]
The elements of Group 3 elements of the periodic table here are Sc, Y, lanthanoid elements (La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. ), Actinoid elements (Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr). Among these, Sc: scandium, Y: yttrium, La: lanthanum, Ce: cerium, Pr: praseodymium, and Nd: neodymium are preferable because particularly excellent battery characteristics are obtained, but are not limited thereto.
[0032]
When such an alloy is used as the negative electrode material, the positive electrode active material is MnO.₂, MoO_Three, V₂O_Five, Li_xCoO₂, Li_x  NiO₂, Li_xMn₂O_FourMetal oxides such as TiS₂, MoS₂, NbSe_ThreeMetal chalcogenides such as polyacene, graphite intercalation compounds such as polyacene, polyparaphenylene, polypyrrole and polyaniline, and alkali metal ions such as conductive polymers, and various substances capable of absorbing and releasing anions can be used.
[0033]
In particular, from the viewpoint of high energy density, V₂O_Five, MnO₂, Li_xCoO₂, Li_xNiO₂, Li_xMn₂O_FourThose having an electrode potential of 3 to 4 V, such as, are preferred. Especially Li_xCoO₂, Li_xNiO₂, Li_xMn₂O_FourLithium-containing transition metal oxides such as are preferred.
[0034]
On the other hand, when such an alloy is used as a positive electrode active material, the negative electrode material contains lithium such as lithium metal, lithium alloy, a carbonaceous material capable of inserting and extracting lithium ions or lithium metal, a chalcogen compound, and methyllithium. Organic compounds and the like can be used. In addition, by using the alloy in combination with lithium metal, a lithium alloy, or an organic compound containing lithium, it is possible to insert lithium into the A phase portion inside the battery.
[0035]
In addition, it is preferable to use an organic electrolyte as the electrolyte. Examples of the organic solvent for the organic electrolyte include esters such as propylene carbonate, ethylene carbonate, butylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, and γ-butyrolactone, substituted tetrahydrofuran such as tetrahydrofuran and 2-methyltetrahydrofuran, and dioxolane. , Ethers such as diethyl ether, dimethoxyethane, diethoxyethane, methoxyethoxyethane, dimethyl sulfoxide, sulfolane, methyl sulfolane, acetonitrile, methyl formate, methyl acetate, N-methylpyrrolidone, dimethylformamide, etc. It can be used alone or as a mixed solvent. The supporting electrolyte salt is LiClO._Four, LiPF₆, LiBF_Four, LiAsF₆, LiCF_ThreeSO_Three, LiN (CF_ThreeSO₂)₂, LiN (C₂F_FiveSO₂)₂, LiN (CF_ThreeSO₂) (C_FourF₉SO₂These can be used alone or as a mixed salt. On the other hand, as the polymer solid electrolyte, a material obtained by dissolving the above supporting electrolyte salt in a polymer such as polyethylene oxide or a crosslinked product thereof, polyphosphazene or a crosslinked product thereof can be used. In addition, Li_ThreeInorganic solid electrolytes such as N and LiI can also be used. That is, any lithium ion conductive non-aqueous electrolyte may be used.
[0036]
Claim2As described in the above, when the hydroxide ion is a reaction involved in the electrode reaction, the A phase capable of electrochemically storing and releasing hydrogen includes, for example, LaNi₅And MmNi₅(However, Mm is a misch metal in which a part of La is replaced with Ce, Pr, Nd and other rare earth elements), an AB5 type alloy in which these Nis are replaced with metal elements such as Al, Co, Mn, and Ti. An AB2 type alloy such as a -Mn alloy or Ti-V alloy, an A2B type alloy such as an Mg-Ni alloy, an alloy in which some of the constituent elements of these alloys are replaced with other metal elements, and the like are preferable. The charging and discharging reaction of these alloys proceeds at a potential very close to the hydrogen potential of about 0.1 V with respect to the standard hydrogen electrode potential. On the other hand, the B phase having electronic conductivity and electrochemically inactive in the charge / discharge potential range is particularly a metal, intermetallic compound or solid solution containing at least one kind of common element with the A phase. Although not limited, in particular, any one of the elements contained in the A phase, or any of the elements contained in the A phase, and a metal element or a semi-group of Groups 2 to 16 of the periodic table A metal element that is an alloy with at least one metal element and that cannot electrochemically occlude / release hydrogen can be suitably used.
[0037]
For example, Mm_1.0Ni_4.0Co_0.5Mn_0.2Al_0.3A solid solution of an AB5 type alloy having a composition represented by Nickel alone is excellent in electron conductivity, but hardly hydrogenates. Mm_1.0Ni_4.0Co_0.5Mn_0.2Al_0.3Since nickel contains nickel, it is possible to form an alloy with nickel alone in any composition. Mm like this_1.0Ni_4.0Co_0.5Mn_0.2Al_0.3When hydrogen is occluded in an alloy of an AB5 type alloy having a composition represented by the following formula and nickel alone, the hydrogenation of the AB5 type alloy portion proceeds, but the nickel simplex portion is maintained with electronic conductivity. That is, a large matrix having an electron conductivity made of nickel alone is formed in the alloy, and the AB5 type alloy in the matrix absorbs and releases hydrogen, so that the charge / discharge reaction proceeds. It is considered that the phenomenon of pulverization or dropout is suppressed, and the overvoltage associated with hydrogen storage / release is reduced.
[0038]
When such an alloy is used as the negative electrode material, the positive electrode active material is Ni (OH).₂Can be suitably used.
[0039]
As the electrolyte, a water-based alkaline electrolyte can be suitably used. Examples of the solute used in the aqueous alkaline electrolyte include KOH, NaOH, LiOH, and the like. These can be used alone or in combination, but it is particularly preferable to use at least KOH.
[0040]
【Example】
Examples of the present invention will be described below.
[0041]
Example 1
Cerium and silicon were mixed at a weight ratio of 57:43 (element ratio 13:87) and heated to 1620 ° C. in an argon atmosphere using an induction furnace. After cooling, the obtained substance was pulverized in a mortar to form a powder. The X-ray diffraction pattern of this powder is shown in FIG. In FIG. 1, (a) is an X-ray diffraction diagram of silicon powder, and (b) is a reagent CeSi.₂(C) is an X-ray diffraction pattern of the substance obtained in this example. As apparent from FIG. 1, it was found that the material obtained above was an alloy of silicon and cerium silicide.
[0042]
In order to investigate the possibility of occlusion of lithium in the alloy, 100 mg of the alloy was sandwiched between two nickel meshes of 10 mm in length and 10 mm in width, and lead wires were attached to form a working electrode for a three-terminal cell. The following operations were performed in dry air, and all materials were used after sufficiently drying in advance. Both the counter electrode and the reference electrode were used by pressing metal lithium having an appropriate size on a nickel plate. LiClO_FourA three-terminal cell (A) was prepared using a propylene carbonate solution in which 1 was dissolved at a concentration of 1 mol / liter as an electrolyte.
[0043]
For comparison, a three-terminal cell (B) was produced in the same manner as in Example 1 except that 100 mg of granular silicon was used instead of the alloy.
[0044]
By flowing a current of 1 mA between the counter electrode of each of the three-terminal cell (A) and the three-terminal cell (B), the potential of the working electrode is set in the range of 0.00 to 2.00 V. Repeated cyclic voltammogram (CV) measurements were taken.
[0045]
As a result, it was confirmed that lithium was occluded / released in the three-terminal cell (A), and the reversible capacity was 800 mAh / g. On the other hand, in the three-terminal cell (B), almost no lithium was occluded and released, and lithium deposition was observed on the working electrode. As is apparent from the results, when the alloy of silicon and silicon-3 group element alloy according to the present invention is used as the negative electrode material, it is expected that a battery with excellent charge / discharge cycle performance and high capacity can be provided.
[0046]
The alloy was further finely pulverized in a mortar, and a coin-type lithium secondary battery shown in FIG. 3 was produced as follows. The pulverized alloy, acetylene black and polytetrafluoroethylene powder were mixed at a weight ratio of 85: 10: 5, and toluene was added and kneaded sufficiently to obtain a clay-like paste. The paste was formed into a sheet having a thickness of 0.3 mm by a roller press. The sheet was punched into a circle having a diameter of 16 mm and heat-treated at 200 ° C. under reduced pressure for 15 hours to obtain a negative electrode 2. The negative electrode 2 was used by being pressure-bonded to the negative electrode can 5 with the negative electrode current collector 7 attached thereto.
[0047]
The positive electrode is LiCoO₂Acetylene black and polytetrafluoroethylene powder were mixed at a weight ratio of 85: 10: 5, and toluene was added and kneaded sufficiently to obtain a clay-like paste. This was formed into a sheet having a thickness of 0.8 mm by a roller press. The sheet was punched into a circle having a diameter of 16 mm and heat-treated at 200 ° C. under reduced pressure for 15 hours to obtain a positive electrode 1. The positive electrode 1 was used by being crimped to a positive electrode can 4 with a positive electrode current collector 6 attached thereto.
[0048]
The electrolyte was LiPF in a mixed solvent of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1.₆Was dissolved at a concentration of 1 mol / liter. As the separator 3, a polypropylene microporous film was used. A coin-type lithium battery having a diameter of 20 mm and a thickness of 1.6 mm was produced using the positive electrode 1, the negative electrode 2, the electrolytic solution, and the separator 3. Reference numeral 8 denotes an insulating packing.
[0049]
A charge / discharge cycle test was conducted using a large number of the coin-type lithium batteries. The test conditions were a charge current of 3 mA, a charge end voltage of 4.2 V, a discharge current of 3 mA, and a discharge end voltage of 3.0 V. As a result, it was found that the capacity of 80% or more with respect to the initial capacity was maintained even after 200 cycles.From the above results, it was found that a lithium secondary battery having a high capacity and excellent cycle characteristics can be provided by using an alloy of silicon and a silicon-3 group element alloy as a negative electrode material.
[0050]
(Example 2) Mm_1.0Ni_4.0Co_0.5Mn_0.2Al_0.3The hydrogen storage alloy and nickel having the following composition were mixed at a weight ratio of 80:20 and heated to 1050 ° C. in an argon atmosphere using an induction furnace. After cooling, the obtained substance was pulverized in a mortar so as to have an average particle diameter of 40 μm to form a powder. The X-ray diffraction pattern of this powder is shown in FIG. In FIG. 2, (a) is an X-ray diffraction diagram of nickel powder, and (b) is the Mm._1.0Ni_4.0Co_0.5Mn_0.2Al_0.3It is an X-ray diffraction diagram of the hydrogen storage alloy having the composition: (c) is an X-ray diffraction diagram of the substance obtained in this example. As is apparent from FIG. 2, it was found that the material obtained in this example was an alloy of the hydrogen storage alloy and nickel.
[0051]
Using the alloy, a nickel-metal hydride battery was prototyped as follows. The alloy powder and methylcellulose 2% aqueous solution were mixed at a weight ratio of 75:25 and sufficiently kneaded to obtain a paste. The paste was uniformly filled in a foamed nickel porous body, dried at 80 ° C., and then pressure-formed by a roller press to obtain a negative electrode 2.
[0052]
The positive electrode 1 is a sintered Ni (OH) produced by a known method.₂An electrode was used. An electrolytic solution in which KOH was dissolved in water at a concentration of 6 mol / liter was used, and a polypropylene nonwoven fabric was used for the separator 3. The positive electrode, the negative electrode, the electrolytic solution, and the separator were spirally wound to produce an AA size cylindrical nickel metal hydride battery.
[0053]
A charge / discharge cycle test was performed using the battery thus prepared. The test conditions were a charging current of 1300 mA, a charging time of 1.15 hours, a discharging current of 1300 mA, and a final discharge voltage of 1.0V. As a result of the charge / discharge test of these batteries, it was found that the capacity of 80% or more was maintained even after 800 cycles.
[0054]
In Example 1, a lithium battery was taken as an example, and performance as a negative electrode active material was particularly shown. In Example 2, a nickel metal hydride battery was taken as an example, and performance as a negative electrode active material was particularly shown. In addition, this invention is not limited to the starting material of the active material described in the said Example, a manufacturing method, a positive electrode, a negative electrode, an electrolyte, a separator, a battery shape, etc.
[0055]
【The invention's effect】
Since the present invention is configured as described above, it is possible to provide an electrode material with little change in crystal system and volume during charge and discharge, reversible charge and discharge, and high electron conductivity. High capacity, high energy density, excellent charge / discharge cycle performance, and excellent battery safety can be provided.
[Brief description of the drawings]
FIG. 1 is an X-ray diffraction pattern of an alloy used in a battery of the present invention.
FIG. 2 is an X-ray diffraction pattern of an alloy used in the battery of the present invention.
FIG. 3 is a cross-sectional view of the battery of the present invention.
[Explanation of symbols]
1 Positive electrode
2 Negative electrode
3 Separator
4 Positive electrode can
5 Negative electrode can
6 Positive current collector
7 Negative electrode current collector
8 Insulation packing

Claims (3)

In a battery including a positive electrode, a negative electrode, and an electrolyte, and a charge / discharge reaction is a reaction in which lithium ions are involved in an electrode reaction, at least one of the positive electrode and the negative electrode is an alloy (provided that the alloy is added before solidification) And the alloy is composed of an alloy of an A phase and a B phase, and the A phase and the B phase contain silicon as at least one common element, The phase A is made of a metal, intermetallic compound or solid solution that can electrochemically occlude and release lithium, and the phase B contains a group 3 element (excluding Nd) and has electronic conductivity, A battery comprising a metal, an intermetallic compound, or a solid solution that is electrochemically inactive in the battery in a charge / discharge potential range of the battery. In a battery comprising a positive electrode, a negative electrode, and an electrolyte , wherein the charge / discharge reaction is a reaction in which hydroxide ions are involved in the electrode reaction, at least one of the positive electrode and the negative electrode includes an alloy, and the alloy is A An alloy of a phase and a B phase, wherein the A phase and the B phase contain at least one or more common elements, the A phase contains Ni, and is a metal capable of electrochemically storing and releasing hydrogen , It is composed of an intermetallic compound or a solid solution, and the B phase is composed of a metal, an intermetallic compound, or a solid solution that has electronic conductivity and is electrochemically inactive in the battery in the charge / discharge potential range of the battery. Battery characterized. The battery according to claim 1, wherein the Group 3 element is cerium.

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