JP5764395B2 - Secondary battery electrode material and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrode material for a secondary battery and a method for manufacturing the same, and more particularly to an electrode material used for a secondary battery such as a lithium ion secondary battery and a method for manufacturing the same.

  A lithium ion secondary battery is a type of non-aqueous electrolyte secondary battery that uses lithium, a lithium alloy, or a material capable of occluding lithium as a negative electrode active material, and has a high voltage, light weight, and high energy density. It is used as a secondary battery for information devices such as mobile phones. In recent years, demand for lithium ion secondary batteries has increased as secondary batteries for large power vehicles such as secondary batteries for hybrid vehicles. In order to further reduce the size and weight, the energy density of lithium ion secondary batteries has increased. Various studies have been conducted on improvement (high capacity).

  Conventionally, as a negative electrode material of a lithium ion secondary battery, a carbonaceous material such as non-graphitizable carbon or graphite having a relatively high capacity and good charge / discharge cycle characteristics has been widely used. There is a problem of further increasing the capacity of the negative electrode material of the battery.

  However, it is known that even if the capacity of the negative electrode material is increased in order to increase the capacity of the lithium ion secondary battery, the graphite-based carbonaceous material has a theoretical limit of a discharge capacity of 372 mAh / g. Approaching the limit. On the other hand, the non-graphite-based carbonaceous material has a drawback that although the discharge capacity is large, the irreversible capacity is large and a large loss occurs at the stage of battery design.

  In addition, a large-capacity negative electrode material that can be used as a substitute for a carbonaceous material has also been proposed, and as a negative electrode material that can have a higher capacity than a carbonaceous material, a certain metal is electrochemically alloyed with lithium and reversibly formed. The use of materials that generate and decompose has been studied. For example, although negative electrode materials such as Li—Al alloys and Si alloys have been reported, these alloys expand and contract with charge / discharge, and thus have a problem that charge / discharge cycle characteristics are extremely poor.

  In order to solve this problem, a method of obtaining a negative electrode material in which Sn is combined with various elements such as Co, Fe, Ni, V, Cu, and Cr has been proposed. For example, by mixing a Sn compound, a transition metal compound, a mixed solution containing a complexing agent and a reducing agent, and then oxidizing the reducing agent to synthesize an Sn alloy, Sn alloy powder can be used as a negative electrode material for a secondary battery. A method of obtaining (for example, refer to Patent Document 1), rapid solidification such as strip casting method (roll quench method), gas atomization method, water atomization method, rotating electrode method, etc. A method of obtaining a negative electrode material powder by pulverizing a material treated by the method as necessary (see, for example, Patent Document 2), a mixed powder of Sn powder and Co powder was treated in a ball mill for 25 hours or more in argon gas A method for obtaining an alloyed metal material of 75 μm or less by classification (for example, see Patent Document 3), adding a metal raw material containing Sn. The molten metal obtained by melting is heat treated as a flake by the melt spinning method and then pulverized by a cup mill to obtain a powder having an average particle size of 15 μm (see, for example, Patent Document 4). There has been proposed a method for obtaining a powder having an average particle size of 0.5 to 2.3 μm by treating with a pot mill for 1 week in a gas (see, for example, Patent Document 5).

JP 2001-332254 A (paragraph numbers 0013 and 0017) JP 2006-236835 A (paragraph numbers 0010 and 0035) JP 2001-143761 A (paragraph number 0044) JP 2004-111202 A (paragraph number 0050) JP 2010-161078 A (paragraph number 0029)

  However, in the method of Patent Document 1, it is necessary to provide many tanks for the reaction, and it is necessary to carry out the reaction in an inert gas atmosphere in the tanks. Further, since a complexing agent and a reducing agent are required in addition to the metal raw material, there is a problem that the manufacturing cost is increased and the productivity is poor. In the methods of Patent Documents 2 and 4, it is necessary to suppress oxidation by performing each process from melting metal to obtaining a powder in an inert gas atmosphere. Atomizing equipment is required, and there is a problem that equipment costs increase. Further, the methods of Patent Documents 3 and 5 have a problem that the processing time becomes long and the productivity is poor because the alloy is mechanically alloyed using a mill.

  Moreover, since the specific surface area of the electrode material for a secondary battery increases as the average particle size decreases, and the efficiency of the battery reaction can be improved, a secondary battery electrode material with a small average particle size is desired. ing. Also, as the average particle size is smaller, the volume expansion during Li occlusion in the negative electrode, that is, the effect of volume expansion associated with the reaction of Sn and Li can be relaxed, and good charge / discharge cycle characteristics can be obtained. A secondary battery electrode material having a small particle size, preferably a secondary battery electrode material having an average particle size of several tens of nanometers or less is desired. However, in the methods of Patent Documents 1 to 5, the average particle size is several tens of nanometers. An electrode material of nm or less cannot be obtained.

Accordingly, the present invention has been made in view of such conventional problems, and an object of the present invention is to provide an electrode material for a secondary battery that has a small average particle size and can improve battery reaction efficiency and charge / discharge cycle characteristics. To do. Another object of the present invention is to provide a method capable of producing such an electrode for a secondary battery at low cost and high productivity.

  As a result of diligent research to solve the above problems, the present inventors have found that at least one selected from the group consisting of hydroxides of Sn and transition metals and rare earth elements (including Y, Al, Si, Zr). After generating particles containing the additive elements, and drying the obtained particles, the average particle size is reduced by heating in a reducing gas atmosphere, improving the battery reaction efficiency and charge / discharge cycle characteristics It has been found that an electrode material for a secondary battery that can be manufactured at low cost and with high productivity, and has completed the present invention.

  That is, the method for producing an electrode material for a secondary battery according to the present invention includes at least one additive selected from the group consisting of Sn and transition metal hydroxides and Al, Si, Zr, and rare earth elements (including Y). Particles containing the element are generated, and the obtained particles are dried and then heated in a reducing gas atmosphere.

  In this method for producing an electrode material for a secondary battery, the generation of particles may be performed by mixing a solution in which an additive element is dissolved after mixing a solution in which Sn and a transition metal are dissolved with an alkali solution, or Sn. The solution in which the transition metal is dissolved and the solution in which the additive element is dissolved may be mixed and then mixed with the alkali solution, or the solution in which Sn and the transition metal are dissolved and the alkali solution in which the additive element is dissolved are mixed. It may be done by.

  In the method for producing an electrode material for a secondary battery, the solution in which Sn and transition metal are dissolved is selected from the group consisting of Sn salt and Co, Ni, Fe, Cu, Cr, In, Ag, and Ti. A solution in which one or more transition metal salts are dissolved in a solvent is preferable. Moreover, it is preferable that the temperature of a heating is 210-600 degreeC.

  The electrode material for a secondary battery according to the present invention includes Sn, one or more transition metal elements selected from the group consisting of Co, Ni, Fe, Cu, Cr, In, Ag, and Ti, and Al, Si. , Zr and a metal powder with one or more additive elements selected from the group consisting of rare earth elements (including Y), and having an average particle size of 10 to 400 nm.

  In this secondary battery electrode material, the oxygen concentration in the metal powder is preferably 0.1 to 20% by mass, and the ratio of the transition metal content to the Sn content in the metal powder (transition metal / Sn ) Is preferably 0.2 to 3.0, and the content of the additive element in the metal powder is preferably 0.1 to 30% by mass. Moreover, it is preferable that the crystallite diameter of a metal powder is 50 nm or less. Moreover, it is preferable that an average particle diameter is 200 nm or less, and it is more preferable that it is smaller than 100 nm. Furthermore, the BET diameter of the metal powder is preferably 2 to 200 nm, and more preferably 50 nm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the electrode material for secondary batteries which has a small average particle diameter and can improve the efficiency of a battery reaction and charging / discharging cycling characteristics can be manufactured at low cost and with high productivity.

It is a figure which shows the X-ray-diffraction pattern of the CoSn alloy powder obtained by the Example and the comparative example. 4 is a transmission electron microscope (TEM) photograph of the CoSn alloy powder obtained in Example 2. FIG. 6 is a transmission electron microscope (TEM) photograph of the CoSn alloy powder obtained in Example 5. FIG.

  In the embodiment of the method for producing a secondary battery electrode material according to the present invention, one or more selected from the group consisting of Sn and transition metal hydroxides and Al, Si, Zr and rare earth elements (including Y) The particles containing the additive element are generated, and the obtained particles are dried and then heated in a reducing gas atmosphere.

  The generation of the particles may be performed by mixing a solution in which Sn and transition metal are dissolved, and then mixing a solution in which the additive element is dissolved after mixing the solution in which Sn and transition metal are dissolved. The mixing may be performed by mixing the solution in which the additive element is dissolved and then mixing the alkali solution, or by mixing the solution in which Sn and the transition metal are dissolved with the alkali solution in which the additive element is dissolved. Also good.

  The solution in which Sn and transition metal are dissolved dissolves Sn salt and one or more transition metal salts selected from the group consisting of Co, Ni, Fe, Cu, Cr, In, Ag, and Ti in a solvent. Can be obtained. The ratio between the amount of Sn salt and the amount of transition metal salt may be adjusted according to the composition of the Sn alloy powder to be produced. It is preferable to use water as the solvent in consideration of cost and environment. The total metal concentration of Sn and transition metal in the solution is preferably 0.01 to 10 mol / L. When the metal concentration exceeds 10 mol / L, the productivity is excellent, but the alloy concentration is too high, and there is a risk that it is difficult to form a fine precursor, and the metal concentration is 0.01 mol / L. When it is less than L, the productivity is deteriorated.

  The alkaline solution can be obtained by dissolving an alkali hydroxide such as NaOH or KOH, a carbonate such as sodium carbonate, ammonia or the like in a solvent. It is preferable to use water as the solvent in consideration of cost and environment.

  By mixing a solution in which Sn and transition metal are dissolved and an alkali solution, a slurry containing Sn and transition metal hydroxide particles is obtained. The temperature of the solution immediately after mixing is preferably 10 to 60 ° C. If the temperature of the solution immediately after mixing exceeds 60 ° C., the particle diameter of the precursor becomes too large, and there may be a problem that the alloy particles and crystallite diameter after reduction also increase. Moreover, when the temperature of the solution immediately after mixing is lower than 10 ° C., a cooling device for controlling the reaction temperature is required, which is not preferable from the viewpoint of productivity. Moreover, it is preferable to stir the solution during and after mixing.

  The solution in which the additive element is dissolved is obtained by dissolving a compound of one or more elements selected from the group consisting of Al, Si, Zr, and a rare earth element (including Y) in a solvent. It is preferable to use water as the solvent in consideration of cost and environment. The solution in which the additive element is dissolved is mixed with a solution in which Sn and transition metal are dissolved and an alkali solution to form Sn and transition metal hydroxide particles, and then mixed with the slurry containing the hydroxide particles. Particles containing Sn and transition metal hydroxide and additive elements may be generated, or mixed with a solution in which Sn and transition metal are dissolved, and then mixed with an alkali solution to produce Sn and transition metal hydroxide. And particles containing the additive element may be generated. Alternatively, a solution in which Sn and transition metal are dissolved in addition to the additive element may be mixed with an alkali solution to produce particles containing Sn and transition metal hydroxide and the additive element, or an alkali in which the additive element is dissolved. The solution may be mixed with a solution in which Sn and transition metal are dissolved to produce particles containing Sn and transition metal hydroxide and an additive element.

  The additive element is at least one element selected from the group consisting of Al, Si, Zr, and rare earth elements (including Y), and is preferably an element having a standard oxidation-reduction potential of −0.8 V or less. An alloy powder composed of Sn and a transition metal can be reduced to a metal in the reduction treatment step, but an additive element having a standard oxidation-reduction potential of −0.8 V or less is a reducing gas such as hydrogen gas or carbon monoxide gas. By virtue of this, it is present as an oxide without being reduced to a metal, so that a sintering preventing effect can be obtained.

  It is preferable to use a water-soluble compound as the compound of the additive element. For example, when the additive element is Al, a water-soluble aluminum salt such as aluminate such as sodium aluminate, aluminum nitrate or aluminum sulfate is used. When the additive element is Si, a silicate such as sodium silicate can be used. When the additive element is Y, Zr or rare earth, yttrium sulfate, yttrium nitrate, zirconium nitrate, Sulfuric acid such as lanthanum nitrate, nitrate, rare earth-sulfuric acid, nitrates and the like can be used.

  A part of the compound of the additive element is taken into the Sn and transition metal hydroxide particles, and the remaining compound of the additive element exists in the liquid phase of the slurry and is separated as a filtrate. Thus, the ratio taken in the hydroxide particles varies depending on the production conditions. Moreover, what is necessary is just to adjust the addition amount of the compound of an addition element according to content of the addition element in the target alloy powder of Sn and a transition metal.

  A slurry containing Sn and transition metal hydroxide and additive element can be obtained by solid-liquid separation of the thus obtained slurry of particles containing Sn and transition metal hydroxide and additive element. . This solid-liquid separation can be performed by a known method such as filtration using a Buchner funnel or centrifugal separation. The obtained cake may be washed with pure water or the like. Thereafter, the cake is dried to obtain a powder containing Sn and transition metal hydroxide and an additive element. This drying can be performed by a known method such as heat drying or vacuum drying.

  The Sn alloy powder can be obtained by heating the powder containing Sn and transition metal hydroxide and the additive element thus obtained in a reducing gas atmosphere. As the reducing gas, hydrogen, a mixed gas of nitrogen and hydrogen, carbon monoxide, or the like can be used. In particular, it is preferable to use hydrogen gas in consideration of reducing power and safety.

  The heating temperature is preferably 210 to 600 ° C. If the heating temperature is lower than 210 ° C, the hydroxide powder may not be sufficiently reduced. If the heating temperature exceeds 600 ° C, particle growth may progress and the particle size or crystallite size may increase, and the charge / discharge cycle There is a risk that the characteristics will deteriorate. In order to obtain an Sn alloy powder having a small average particle size, the heating temperature is preferably 210 to 500 ° C, more preferably 250 to 300 ° C. The heating time is preferably 0.5 hours or longer. If the heating time is shorter than 0.5 hour, the target product phase may not be obtained without sufficient reduction.

  According to the embodiment of the method for manufacturing a secondary battery electrode material described above, Sn and one or more transition metal elements selected from the group consisting of Co, Ni, Fe, Cu, Cr, In, Ag, and Ti , Al, Si, Zr, and an electrode material for a secondary battery having a mean particle diameter of 10 to 400 nm (including a metal powder containing one or more additive elements selected from the group consisting of rare earth elements (including Y)) Negative electrode material) can be manufactured.

  The secondary battery electrode material (negative electrode material) is selected from the group consisting of Sn, which is an element alloyed with Li, and Co, Ni, Fe, Cu, Cr, In, Ag, and Ti, which are difficult to alloy with Li. And at least one transition metal element and one or more additive elements selected from the group consisting of Al, Si, Zr and rare earth elements (including Y) for suppressing coarsening of the particle diameter. It consists of metal powder (preferably Sn alloy powder). In a secondary battery using only Sn, which is an element alloyed with Li, as a metal element constituting the negative electrode material, a large volume change is caused when Sn is alloyed with Li, so that charge / discharge cycle characteristics are poor. There is a problem, but in a secondary battery using a negative electrode material containing a metal material in which a transition metal element difficult to alloy with Li coexists with Sn, volume change as the negative electrode material is suppressed, and charge / discharge cycle characteristics deteriorate. Can be prevented. In addition, a powder having a small average particle diameter can be obtained by including one or more elements selected from the group consisting of Al, Si, Zr, and rare earth elements (including Y).

  The metal powder (preferably Sn alloy powder) containing Sn, a transition metal element, and an additive element is selected from the group consisting of A / Sn (A is Co, Ni, Fe, Cu, Cr, In, Ag, and Ti). It is preferred that the one or more transition metal elements) be in the range of 0.2 to 3.0. When the composition ratio A / Sn is less than 0.2, the Sn ratio is too large, and the volume change of the negative electrode material during charge / discharge cannot be sufficiently suppressed, and the Sn alloy powder is used as the negative electrode material. As a result, the charge / discharge cycle characteristics of the battery used may deteriorate. On the other hand, when the composition ratio A / Sn exceeds 3.0, the ratio of Sn is too small, and the capacity of a battery using the metal powder as a negative electrode material may be small. The composition ratio A / Sn is more preferably 0.5 to 2.5.

  The transition metal element of the metal powder preferably contains Co. By including Co, it is possible to obtain a negative electrode material of a metal element which is difficult to be alloyed with Li and has high conductivity. The metal powder mainly includes an alloy phase, but may include a plurality of types of alloy phases, and may include Sn and a transition metal in a single phase.

  The content of the additive element in the metal powder is preferably 0.1 to 30% by mass, and more preferably 2 to 20% by mass. If the amount is less than 0.1% by mass, the average particle size of the metal powder may increase. If the amount exceeds 30% by mass, the proportion of Sn that contributes as a negative electrode is decreased due to the excessive proportion of the additive element. There may be a problem of lowering.

  In a powder containing Sn and transition metal hydroxide and an additive element in a state before the reduction treatment, the additive element is in a state of being bonded to oxygen in the case of Al, Zr or a rare earth element (including Y). It is thought to exist in the form of hydroxide. Oxygen combined with the additive element cannot be removed by reduction treatment, and oxygen is contained in the metal powder. The oxygen concentration (oxygen content) is preferably 20% by mass or less, and more preferably 10% by mass or less. When the oxygen content exceeds 20% by mass, the reduction is not sufficient, and there is a high possibility that it is an oxide of Sn and a transition metal, and the irreversible capacity may increase or the charge / discharge cycle characteristics may deteriorate. is there. In addition, it is difficult to make this oxygen content less than 0.1 mass%.

  The average particle size of the Sn, transition metal element, and additive element metal powder (preferably Sn alloy powder) is preferably 2 to 400 nm. When the average particle diameter exceeds 400 nm, when metal powder is used as the negative electrode material, the efficiency of the battery reaction may be lowered, and the charge / discharge cycle characteristics may be deteriorated. On the other hand, if the average particle size is smaller than 2 nm, there is a possibility that problems such as inconvenience in handling and the fact that metal particles are very easy to oxidize may occur. Considering the efficiency of the battery reaction and charge / discharge cycle characteristics when the metal powder is used as the negative electrode material, the average particle size is preferably 100 nm or less, more preferably 60 nm or less, and 40 nm or less. Is most preferred.

  The crystallite diameter of the metal powder (preferably Sn alloy powder) of Sn, transition metal element and additive element is preferably 50 nm or less. The smaller the crystallite diameter, the better. On the other hand, when the crystallite diameter exceeds 50 nm, the volume change of the negative electrode material during charge / discharge cannot be sufficiently suppressed, and the charge / discharge cycle characteristics of the battery using the metal powder as the negative electrode material deteriorate. There is.

  The BET diameter of the Sn, transition metal element, and additive element metal powder (preferably Sn alloy powder) is preferably 2 to 200 nm. When the BET diameter exceeds 200 nm, when metal powder is used as the negative electrode material, battery reaction efficiency may be lowered, and charge / discharge cycle characteristics may be deteriorated. On the other hand, when the BET diameter is smaller than 2 nm, there is a possibility that problems such as inconvenience in handling and in which metal particles are very easily oxidized are caused. Considering the efficiency of the battery reaction and charge / discharge cycle characteristics when the metal powder is used as the negative electrode material, the BET diameter is preferably 50 nm or less, more preferably 30 nm or less, and 20 nm or less. Most preferred.

  The negative electrode for lithium ion secondary batteries can be manufactured by a well-known method using the metal powder mentioned above. For example, an appropriate binder is mixed with the above-described metal powder, and an appropriate conductive powder is mixed as necessary to improve conductivity. A solvent in which the binder is dissolved is added to this mixture, and if necessary, the mixture is sufficiently stirred with a known stirrer to form a slurry. The slurry is applied to an electrode substrate (current collector) such as a rolled copper foil with a doctor blade or the like, dried, and then consolidated by roll rolling or the like to produce a negative electrode for a non-aqueous electrolyte secondary battery.

  Although it is preferable to produce a lithium ion secondary battery using the negative electrode thus produced, other nonaqueous electrolyte secondary batteries can also be produced. The lithium ion secondary battery includes a negative electrode, a positive electrode, a separator, and a non-aqueous electrolyte as a basic structure, but uses a negative electrode manufactured as described above and a known positive electrode, separator, and electrolyte. A lithium ion secondary battery can be manufactured.

  Examples of the secondary battery electrode material and the method for manufacturing the same according to the present invention will be described below in detail.

[Example 1]
An aqueous solution containing Co and Sn by dissolving 28.11 g of cobalt sulfate heptahydrate (CoSO ₄ · 7H ₂ O) and 35.06 g of tin (IV) chloride (SnCl ₄ · 5H ₂ O) in 400 g of pure water. Produced. Moreover, 54.22g of 48.5 mass% sodium hydroxide aqueous solution was added to 200g of pure water, and alkaline aqueous solution was produced. The aqueous solution containing Co and Sn is heated and maintained at 40 ° C. and stirred, and the alkaline aqueous solution is heated to 40 ° C. and added to the aqueous solution containing Co and Sn. A slurry containing the product was obtained.

  Further, 10.6 g of sodium aluminate (manufactured by Wako Pure Chemical Industries, Ltd., molar ratio (Al / Na) = 0.79) was added to 130 g of pure water to prepare a sodium aluminate aqueous solution. The aqueous sodium aluminate solution was added to the slurry containing Co and Sn hydroxides and stirred to obtain a slurry containing Co, Sn and Al hydroxides. The slurry was filtered and washed with pure water to obtain a Co, Sn, and Al hydroxide cake. The Co, Sn, and Al hydroxide cake was dried in the atmosphere at 140 ° C. for 3 hours and then reduced in a hydrogen atmosphere at 300 ° C. for 3 hours to obtain a CoSn alloy powder.

  About the obtained CoSn alloy powder, the range of 20 to 70 ° / 2θ was measured with a Cu radiation source (40 kV / 30 mA) using an X-ray diffractometer (XRD-6100 manufactured by Shimadzu Corporation), and X-ray diffraction (XRD) Was evaluated. An X-ray diffraction pattern of the CoSn alloy powder obtained in this example is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase.

  Further, by using the half width β of the (201) plane of the CoSn phase obtained from the X-ray diffraction pattern, the crystallite diameter (Dx) is obtained from Scherrer's equation D = (K · λ) / (β · cos θ). When calculated, the crystallite diameter (Dx) was 23.8 nm. In the Scherrer equation, D is the crystallite diameter (nm), λ is the measured X-ray wavelength (nm), β is the diffraction width spread by the crystallite, θ is the Bragg angle of the diffraction angle, and K is the Scherrer constant. In this equation, the measurement X-ray wavelength λ is 1.54 nm, and the Scherrer constant K is 0.9.

  Further, the CoSn alloy powder obtained in this example was photographed at a magnification of 174,000 with a transmission electron microscope (JEM-100CX manufactured by JEOL Ltd.), and the obtained transmission electron micrograph (TEM image). The major axis diameter of each of 50 CoSn alloy powder particles was measured, and the average value was taken as the average particle diameter of the CoSn alloy powder. As a result, the average particle diameter of the obtained CoSn alloy powder was 28.6 nm. The “major axis diameter” means that the minimum distance when a particle image is sandwiched between two parallel lines is the minor axis diameter, and the particle image is sandwiched between two parallel lines orthogonal to the minor axis diameter. The interval.

Further, for the CoSn alloy powder obtained in this example, a specific surface area (BET value) was determined by a BET 1-point method using a specific surface area measuring device (MONOSORB manufactured by Cantachrome), and a BET diameter = 6 / (ρs × 10 ⁶ × BET value) × 10 ⁹ (wherein ρs is the particle density = 8.5 g / cm ³ ), the BET diameter was determined. As a result, the BET diameter of the obtained CoSn alloy powder was 6.2 nm.

  In addition, the CoSn alloy powder obtained in this example was sealed in a sealed container in an inert gas atmosphere, and the oxygen concentration of the CoSn alloy powder was measured using a simultaneous oxygen / nitrogen analyzer (TC-436 manufactured by LECO). Was 4.1% by mass.

  Further, the CoSn alloy powder obtained in this example was dissolved in an acid, and the composition ratio (mass) of Co, Sn, and Al was determined from the measurement result using an ICP emission spectroscopic analyzer (SPS-3520V manufactured by SII Nanotechnology). Ratio), and the content of each element in the CoSn alloy powder was calculated from this mass ratio and the above oxygen concentration. As a result, the contents of Sn, Co and Al in the obtained CoSn alloy powder were 61.5 mass%, 30.5 mass% and 3.9 mass%, respectively.

  These results are shown in Table 1.

[Example 2]
A CoSn alloy powder was produced in the same manner as in Example 1 except that the reduction time was set to 6 hours. Evaluation by an X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, calculation of BET diameter, The oxygen concentration was measured and the content of each element was calculated. A transmission micrograph (TEM image) of the CoSn alloy powder obtained in this example is shown in FIG. 2, and an X-ray diffraction pattern is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter is 10.7 nm, the average particle diameter is 12.3 nm, the BET diameter is 6.0 nm, the oxygen concentration is 6.6% by mass, and the contents of Sn, Co, and Al are 59.8 respectively. They were mass%, 29.7 mass%, and 4.0 mass%. These results are shown in Table 1.

[Example 3]
An aqueous solution containing Co and Sn by dissolving 28.11 g of cobalt sulfate heptahydrate (CoSO ₄ · 7H ₂ O) and 35.06 g of tin (IV) chloride (SnCl ₄ · 5H ₂ O) in 400 g of pure water. Produced. Moreover, 54.22g of 48.5 mass% sodium hydroxide aqueous solution and 8.2g of sodium aluminate (the Wako Pure Chemical Industries Ltd. make, molar ratio (Al / Na) = 0.79) were added to the pure water 200g. An alkaline aqueous solution was prepared. The aqueous solution containing Co and Sn is heated to 40 ° C. and stirred, and the alkaline aqueous solution is heated to 40 ° C. and added to the aqueous solution containing Co and Sn. A slurry containing hydroxide was obtained. The slurry was filtered and washed with pure water to obtain a Co, Sn, and Al hydroxide cake. The Co, Sn, and Al hydroxide cake was dried in the atmosphere at 140 ° C. for 3 hours and then reduced in a hydrogen atmosphere at 400 ° C. for 3 hours to obtain a CoSn alloy powder.

  About the obtained CoSn alloy powder, evaluation by X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, calculation of BET diameter, measurement of oxygen concentration and inclusion of each element in the same manner as in Example 1 The amount was calculated. An X-ray diffraction pattern of the CoSn alloy powder obtained in this example is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter is 13.4 nm, the average particle diameter is 15.0 nm, the BET diameter is 5.9 nm, the oxygen concentration is 5.4% by mass, and the contents of Sn, Co, and Al are 59.7%, respectively. They were mass%, 29.6 mass%, and 5.3 mass%. These results are shown in Table 1.

[Example 4]
A CoSn alloy powder was produced in the same manner as in Example 3 except that the reduction temperature was changed to 500 ° C., evaluated by X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, calculation of BET diameter, The oxygen concentration was measured and the content of each element was calculated. An X-ray diffraction pattern of the CoSn alloy powder obtained in this example is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter is 17.1 nm, the average particle diameter is 18.2 nm, the BET diameter is 8.7 nm, the oxygen concentration is 4.8% by mass, and the contents of Sn, Co, and Al are 60.0%, respectively. It was mass%, 29.8 mass%, and 5.4 mass%. These results are shown in Table 1.

[Example 5]
The same method as in Example 1 except that 10.6 g of sodium aluminate was replaced with 8.5 g of yttrium sulfate octahydrate (Y ₂ (SO ₄ ) ₃ · 8H ₂ O) and the reduction time was 6 hours. Thus, a CoSn alloy powder was manufactured, and evaluation by an X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, calculation of BET diameter, measurement of oxygen concentration, and calculation of content of each element were performed. A transmission micrograph (TEM image) of the CoSn alloy powder obtained in this example is shown in FIG. 3, and an X-ray diffraction pattern is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter was 19.7 nm, the average particle diameter was 26.1 nm, the BET diameter was 11.8 nm, the oxygen concentration was 3.1% by mass, and the contents of Sn, Co, and Y were 60.0%, respectively. Mass%, 29.8 mass%, and 7.2 mass%. These results are shown in Table 1.

[Example 6]
Substituting 10.0 g of sodium aluminate with 10.0 g of anhydrous sodium metasilicate (Na ₂ SiO ₃ ) to obtain a cake of Co and Sn hydroxide and Si from a slurry containing Co and Sn hydroxide and Si In addition, a CoSn alloy powder was produced in the same manner as in Example 1 except that the reduction time was set to 6 hours, evaluation by X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, BET diameter Calculation, measurement of oxygen concentration, and calculation of the content of each element were performed. An X-ray diffraction pattern of the CoSn alloy powder obtained in this example is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter is 15.6 nm, the average particle diameter is 18.1 nm, the BET diameter is 13.3 nm, the oxygen concentration is 3.4% by mass, and the contents of Sn, Co, and Si are 62.8, respectively. They were 3 mass%, 31.2 mass%, and 2.6 mass%. These results are shown in Table 1.

[Comparative Example 1]
A CoSn alloy powder was produced in the same manner as in Example 2 except that the sodium aluminate aqueous solution was not added. Evaluation by an X-ray diffraction pattern, calculation of crystallite diameter, calculation of average particle diameter, calculation of BET diameter Calculation, measurement of oxygen concentration, and calculation of the content of each element were performed. An X-ray diffraction pattern of the CoSn alloy powder obtained in this example is shown in FIG. From this X-ray diffraction pattern, it was confirmed that the CoSn alloy powder obtained in this example was mainly composed of a CoSn phase. The crystallite diameter was 22.9 nm, the average particle diameter was 116.0 nm, and the BET diameter was 72.7 nm, which was larger than those in Examples 1 to 6. The oxygen concentration was 0.3% by mass, and the contents of Sn and Co were 66.6% by mass and 33.1% by mass, respectively. These results are shown in Table 1.

Claims (13)

By mixing a solution in which one or more additive elements selected from the group consisting of Al, Si, Zr and rare earth elements are mixed after mixing a solution in which Sn and transition metal are dissolved with an alkali solution , Sn and transition metal The electrode material for a secondary battery is characterized in that an Sn alloy powder is obtained by producing particles containing a hydroxide and an additive element, and drying the particles, followed by heating in a reducing gas atmosphere. Manufacturing method. Sn and transition metal dissolved solution and Al, Si, by mixing the alkaline solution after the at least one additive element selected from the group consisting of Zr and rare earth elements was mixed with a solution prepared by dissolving, Sn And a transition metal hydroxide and an additive element are formed, and after drying the particles, the resultant is heated in a reducing gas atmosphere to obtain a Sn alloy powder. Method for manufacturing an electrode material. By mixing a solution in which Sn and transition metal are dissolved with an alkali solution in which one or more additive elements selected from the group consisting of Al, Si, Zr and rare earth elements are dissolved , a hydroxide of Sn and transition metal A method for producing an electrode material for a secondary battery , comprising: producing particles containing an additive element; and drying the particles, followed by heating in a reducing gas atmosphere to obtain an Sn alloy powder. The solution in which Sn and transition metal are dissolved dissolves Sn salt and one or more transition metal salts selected from the group consisting of Co, Ni, Fe, Cu, Cr, In, Ag and Ti in a solvent. The method for producing an electrode material for a secondary battery according to any one of claims 1 to 3, wherein the solution is a solution. The method for producing an electrode material for a secondary battery according to any one of claims 1 to 4, wherein the heating temperature is 210 to 600 ° C. Sn, one or more transition metal elements selected from the group consisting of Co, Ni, Fe, Cu, Cr, In, Ag and Ti, and 1 selected from the group consisting of Al, Si, Zr and rare earth elements An electrode material for a secondary battery, comprising an alloy powder with more than one kind of additive element, having an average particle diameter of 10 to 400 nm and a BET diameter of 2 to 200 nm. The electrode material for a secondary battery according to claim 6, wherein an oxygen concentration in the alloy powder is 0.1 to 20% by mass. The secondary ratio according to claim 6 or 7, wherein a ratio of the content of the transition metal to a content of Sn in the alloy powder (transition metal / Sn) is 0.2 to 3.0. Battery electrode material. The secondary battery electrode material according to any one of claims 6 to 8, wherein the content of the additive element in the alloy powder is 0.1 to 30% by mass. The electrode material for a secondary battery according to any one of claims 6 to 9, wherein a crystallite diameter of the alloy powder is 50 nm or less. 11. The electrode material for a secondary battery according to claim 6, wherein an average particle diameter of the alloy powder is 200 nm or less. The electrode material for a secondary battery according to any one of claims 6 to 10, wherein an average particle diameter of the alloy powder is smaller than 100 nm. The secondary battery electrode material according to claim 6, wherein the alloy powder has a BET diameter of 50 nm or less.

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