JP2008123823A - Method of manufacturing electrode material, electrode material, and nonaqueous lithium secondary battery using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the manufacturing method of an electrode material without the need of a pulverizing process of pulverizing large particles into small particles. <P>SOLUTION: In the manufacturing method of an amorphous vanadium oxide or the like usable as the positive electrode material of a nonaqueous lithium secondary battery, a spray drying method is applied so as not to include a pulverizing process of mechanically pulverizing large particles into small particles. By adopting such a method, both of the pulverizing process and a sieving process needed after the pulverizing process are eliminated, manufacture processes are simplified and manufacture costs are reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technology of a lithium secondary battery, and is particularly effective when applied to a non-aqueous lithium secondary battery and a positive electrode material thereof.

  The technology described below has been studied by the present inventors in completing the present invention, and the outline thereof is as follows.

  Conventional non-aqueous lithium secondary batteries use lithium cobaltate, lithium manganate, or lithium nickelate as the positive electrode. The capacity theoretically did not exceed 137 mAh / g, 148 mAh / g, 198 mAh / g and 200 mAh / g.

  Thus, studies are underway to use a vanadium pentoxide-based material having a large number of valences and a high capacity potential as a positive electrode material for a lithium secondary battery. However, since the positive electrode material does not include a lithium ion supply source, it is necessary to use a lithium ion supply source for the negative electrode, and its use is limited to a primary battery or a secondary battery with a very low current amount. It was.

  In addition, when crystalline vanadium pentoxide is used for the positive electrode material, if low-valent vanadium is used to extract a high capacity, the crystal structure collapses due to charge / discharge, and the charge / discharge cycle is repeated. A decrease in capacity occurred.

  On the other hand, in Patent Document 1, an organic sulfur material such as a sulfur-containing conductive polymer is inserted between layers of an insulating layered compound such as vanadium pentoxide, so that the crystal structure of the layered compound is fixed to some extent and phase transformation is performed. It is disclosed that it can suppress. By adopting such a configuration, the capacity characteristics of the layered compound are maximized.

  Further, in such a configuration, an insulating (non-conductive) organic sulfur compound that expands the discharge potential range is also inserted between the layers, so that, for example, a proton of a mercapto group is reduced on the negative electrode to generate hydrogen gas. It is said that high cycle characteristics can be achieved at the same time.

Further, Patent Document 2 has a detailed disclosure showing a flow diagram for a method for producing a positive electrode active material for a non-aqueous lithium secondary battery.
JP 2005-285376 A JP 2002-279984 A

  In the invention described in Patent Document 1, in practice, coarse particles of several tens of μm to several hundreds of μm or more are mixed in the obtained solid, and further micronization is necessary for use as a positive electrode material. is there. Therefore, in order to produce a large amount of active material by such a method, complicated processing steps such as filtration from the reaction solution, drying, subsequent pulverization, and sieving are inevitably necessary.

  In the invention disclosed in Patent Document 2, a slurry formed by wet mixing is spray-dried, then further fired, crushed after firing, and sieved to produce a powder for a positive electrode material. It is stated that such a production method can produce a positive electrode material powder having a particle size distribution of 1 to 20 μm and a maximum particle size of 50 μm or less.

  The inventions described in Patent Documents 1 and 2 are certainly excellent inventions. However, in the production of electrode materials, in any case, a mechanical crushing process for crushing large particles into small particles is required. It was. Further, the electrode material proposed by the present inventor has also been manufactured through a pulverization step after synthesis of the electrode material.

  In addition, when finely pulverizing after drying, for example, by mechanical pulverization, if dry pulverization is performed for a long time, the crystal structure of the active material at the corner may change, and the battery charge / discharge characteristics may be degraded. It was seen.

  While the present inventor is performing technical development to reduce the manufacturing cost of the electrode material proposed in the previous application, although the time reduction of the synthesis process related to the reaction system of the electrode material cannot be easily solved, the grinding process I thought that it would be possible to shorten the time. Such a pulverization process requires a subsequent sieving process, and is a process in which a considerable amount of time is spent in the process.

  An object of the present invention is to shorten the time of the pulverization process when manufacturing the electrode material.

  The objective of this invention is providing the manufacturing method of the electrode material which does not require the grinding | pulverization process which grind | pulverizes a large particle into a small particle.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  Of the inventions disclosed in the present application, the outline of typical ones will be briefly described as follows.

  That is, when the active material of the electrode material is manufactured, the mechanical pulverization step is omitted by applying the spray drying method to the slurry with water.

  Among the inventions disclosed in the present application, effects obtained by typical ones will be briefly described as follows.

  In the present invention, since the slurry having the active material of the electrode material such as vanadium oxide is dried by the spray drying method (also referred to as spray drying method), the mechanical pulverization step after drying is unnecessary. Therefore, the manufacturing process can be simplified, the process time can be shortened, and the manufacturing cost can be reduced.

  In the present invention, as described above, since the slurry having the active material of the electrode material such as vanadium oxide is dried by the spray drying method, it becomes a spherical fine powder that does not require re-grinding, and an electrode having a required density can be produced. Easy to do.

  Since the active material as the electrode material produced by the production method of the present invention is a spherical particle having a certain average particle diameter, it is possible to improve the electrode density and the energy density of the battery.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The present invention is a technique related to the production of an electrode material. In particular, it is a manufacturing technique that does not include a pulverizing step of pulverizing large particles into small particles during the manufacturing process. This manufacturing technique will be described below by taking the positive electrode material of a non-aqueous lithium secondary battery as an example of the electrode material.

  As the active material of the positive electrode material of the non-aqueous lithium secondary battery, a material containing an oxide of at least one metal element selected from Group V elements and Group VI elements in the periodic table can be used. Examples of the metal oxide include vanadium oxide (vanadium oxide) and niobium oxide. In particular, vanadium pentoxide is preferable. Such metal oxides may be made macroscopically amorphous while maintaining a layered crystal structure. More specifically, as schematically shown in FIG. 1, the layer length L1 may be in the range of 1 nm or more and 30 nm or less.

  In the layered crystal state, from the viewpoint of entering and exiting lithium ions between layers, if the layered crystal is less than 1 nm, lithium cannot be inserted or desorbed, and high capacity cannot be taken out. On the other hand, if it exceeds 30 nm, the crystal structure collapses due to charge / discharge, resulting in poor cycle characteristics. Therefore, the layer length is desirably 1 nm or more and 30 nm or less. More preferably, the layer length may be 5 nm or more and 25 nm or less.

  As a result, the path related to the entry / exit of lithium ions between layers is shortened. By adopting such a configuration, it becomes easy for lithium ions to enter and exit between the vanadium oxide layers, and the discharge capacity, cycle characteristics, and the like are improved. As shown in FIG. 2, in the state where the layer length L2 is long, it is difficult for lithium ions to enter and exit between the layers as compared with the case where the layer length L1 is short.

  Note that macroscopic amorphization means that the state of the layered crystalline substance is only a crystal structure with a layer length of 30 nm or less, or such a crystal, from a microscopic viewpoint where the order of nanometers or less can be observed. It is confirmed that the structure and the amorphous structure coexist, but when this state is viewed from a macro viewpoint that can only observe μm orders larger than nm, the amorphous structure with randomly arranged crystal structures The upper limit of the area ratio% of the fine crystal grains observed in the cross section of the layered crystal substance is effective to a value close to 100%. In the case of 100%, a complete amorphous state does not already exist, and only a layered crystal state is obtained. Of course, the layered crystal having a layer length of 1 nm or more and 30 nm or less may be 100%.

  The metal oxide made amorphous as described above is doped with lithium ions. The lithium ions are preferably doped at a molar ratio of 0.1 to 6 with respect to the metal oxide. If the doping amount of lithium ions is less than 0.1 in terms of molar ratio, the doping effect is not sufficiently exhibited, and if the doping amount of lithium ions exceeds 6, the metal oxide may be reduced to metal. Therefore, it is not preferable.

  In the present invention, dope means occlusion, support, adsorption or insertion, and means a phenomenon in which lithium ions enter an electrode active material such as a positive electrode.

  Moreover, when synthesizing the vanadium oxide, a sulfur-containing conductive polymer may be included in the active material. Although details are unknown, when a monomer corresponding to the sulfur-containing conductive polymer is present, this monomer serves to limit the oxygen concentration in the reaction system, thereby keeping the composition ratio of the vanadium oxide constant. It is considered effective. However, since it becomes an impurity for the active material of the final product, it is considered that the performance of the active material is improved by removing it in the spray drying stage.

  The active material used as such a positive electrode material can be synthesized by heating a metal oxide together with a monomer corresponding to a sulfur-containing conductive polymer, if necessary, in water in the presence of a water-soluble lithium ion source. it can. For example, it can be easily synthesized by heating under reflux.

  As the water-soluble lithium ion source, lithium sulfide, lithium hydroxide, lithium selenide, lithium telluride, or the like can be used. What contains at least 1 type of lithium compound chosen from this group should just be used.

  In this way, the water-soluble lithium ion source dissolves in water and exhibits alkalinity, and a metal oxide such as vanadium oxide, which is usually obtained as a crystalline (layered) compound, dissolves in the alkaline aqueous solution and becomes amorphous. At the same time, lithium ions are taken into the amorphous metal oxide. A desired active material can be obtained by applying a spray drying method in which the obtained suspension is refluxed and sprayed using a four-fluid nozzle or the like in a dry atmosphere at a temperature of 100 to 250 ° C. When the drying atmosphere temperature is 100 ° C. or lower, drying becomes insufficient, and fine spherical particles having a size of 0.1 to 20 μm cannot be obtained, and when the temperature is 250 ° C. or higher, the crystal structure changes. It is preferable to carry out within the range.

  In the active material to which the production technique of the present invention is applied, the X-ray diffraction pattern of the contained metal oxide has a peak in the range of the diffraction angle 2θ = 5 to 15 °.

  Such an active material can be mixed with a binder such as polyvinylidene fluoride (PVDF), preferably together with conductive particles to form a positive electrode material, which can be coated on a conductive substrate to produce a positive electrode. The thickness of the coating layer is preferably 10 to 100 μm, for example.

  The conductive particles include conductive carbon (conductive carbon such as ketjen black), copper, iron, silver, nickel, palladium, gold, platinum, indium, tungsten, and other metals, indium oxide, tin oxide. And the like, and the like. Such conductive particles are preferably contained in a proportion of 1 to 30% of the weight of the metal oxide.

  For the substrate (current collector) that supports the coating layer of the positive electrode material, a conductive substrate that exhibits conductivity at least on the surface in contact with the positive electrode material is used. This substrate can be formed of a conductive material such as a metal, a conductive metal oxide, or conductive carbon. In particular, it is preferable to form with copper, gold | metal | money, aluminum, those alloys, or conductive carbon. Alternatively, the base may be configured such that a base body formed of a nonconductive material is covered with a conductive material.

  The active material of the electrode material that can be used as the positive electrode material of such a non-aqueous lithium secondary battery is manufactured by a process that does not include a pulverization step that mechanically pulverizes large particles into small particles, as shown in the flow chart of FIG. The present inventor newly found this possibility.

  That is, as shown in FIG. 3, in step S100, an active material for the positive electrode material of the non-aqueous lithium secondary battery is synthesized. It can be synthesized by mixing required materials with water and heating to reflux for a predetermined time.

  In step S200, the spray drying method is applied to the active material suspension for the positive electrode material thus synthesized. By applying this spray drying method, the active material for the positive electrode material can be made into a fine spherical positive electrode material powder. Such positive electrode material powder is water-soluble.

  That the positive electrode material powder is a spherical particle can be observed, for example, with a scanning electron microscope as shown in FIG. In addition, since the spherical particles fall within the range of a predetermined particle size distribution by applying a spray drying method, for example, as shown in FIG. Can do.

The average particle diameter (D ₅₀ ) of the obtained spherical particles is 0.1 μm or more and 20 μm or less. When the average particle size is smaller than 0.1 μm, it is necessary to increase the binder in order to improve the adhesion at the time of producing the electrode. When the amount of the binder is increased, the resistance increases and the energy density also decreases. If it is larger than 20 μm, the diffusion of lithium ions in the solid of the active material is inhibited, resulting in a disadvantage that the energy density is lowered.

  On the other hand, the conventional manufacturing method is manufactured, for example, according to a flow as shown in FIG. That is, in step S100, the active material for the positive electrode material of the non-aqueous lithium secondary battery is synthesized in the same manner as the manufacturing method of the present invention. The required materials are mixed with water and synthesized by heating under reflux for a predetermined time.

  The active material suspension for the positive electrode material thus synthesized is concentrated, dried and solidified in step S300. In the step of concentration, drying and solidification in step S300, the average particle size is increased, for example, as shown in FIG.

  Therefore, in step S400 shown in FIG. 6, it is mechanically pulverized using a ball mill or the like. The pulverized particles are then sieved in step S500 and dried in step S600 to obtain a positive electrode material powder.

  In the above manufacturing method, large particles are mechanically pulverized into small particles using a ball mill. When such pulverization is performed, spherical particles obtained by spray drying, for example, as shown in FIG. It is confirmed by a scanning electron microscope that the situation is completely different.

  Incidentally, also in the invention described in the above-mentioned Patent Document 2, as shown in FIG. 9, after the wet mixing in the step 2, the spray drying shown in the step 3 is performed, and then the firing in the step 4 and the subsequent steps. The positive electrode material powder is manufactured by crushing 5 and sieving in step 6. In this manufacturing method, in step 5, there is a crushing step corresponding to the crushing step.

  As described above, in the conventional manufacturing method, a step of pulverizing (or crushing) large particles into small particles is necessarily required. However, in the manufacturing method of the present invention, as shown in the flow chart of FIG. 3, there is no pulverizing step for converting large particles into small particles, so that the subsequent sieving step is not necessary, and the process can be greatly shortened. It can be done. Of course, the production cost can also be reduced.

  The “grinding step” referred to in this specification does not include a step of grinding raw materials such as oxides necessary for the synthesis of the active material of the electrode material to which the present invention is applied. As shown in FIGS. 3 and 6, the “pulverization step” in the present specification refers to the pulverization step after the synthesis of the active material to the last.

  By forming a positive electrode using such an active material, a non-aqueous lithium secondary battery can be configured. The non-aqueous lithium secondary battery has a configuration including the positive electrode, a negative electrode, and an electrolyte layer disposed between the positive electrode and the negative electrode.

  In the non-aqueous lithium secondary battery having such a configuration, the negative electrode can be formed of a commonly used lithium-based material. Such lithium-based materials include lithium-based metal materials such as metallic lithium and lithium alloys (for example, Li-Al alloys), intermetallic compound materials of metals such as tin and silicon and lithium metals, and lithium such as lithium nitride. A compound or a lithium intercalation carbon material can be mentioned.

As electrolytes, lithium salts such as CF ₃ SO ₃ Li, C ₄ F ₉ SO ₈ Li, (CF ₃ SO ₂ ) ₂ NLi, (CF ₃ SO ₂ ) ₃ CLi, LiBF ₄ , LiPF ₆ , LiClO _4, etc. Can be used. The solvent that dissolves the electrolyte is a non-aqueous solvent.

  Examples of non-aqueous solvents include chain carbonates, cyclic carbonates, cyclic esters, nitrile compounds, acid anhydrides, amide compounds, phosphate compounds, amine compounds, and the like. Specific examples of the non-aqueous solvent include ethylene carbonate, diethyl carbonate (DEC), propylene carbonate, dimethoxyethane, γ-butyrolactone, n-methylpyrrolidinone, N, N′-dimethylacetamide, acetonitrile, or propylene carbonate and dimethoxyethane. And a mixture of sulfolane and tetrahydrofuran.

  The electrolyte layer interposed between the positive electrode and the negative electrode may be a solution of the above electrolyte in a non-aqueous solvent or a polymer gel (polymer gel electrolyte) containing this electrolyte solution.

  As a configuration of the lithium secondary battery having such a configuration, for example, the configuration of a non-aqueous lithium secondary battery shown in FIG. 10 can be given.

  That is, in the nonaqueous lithium secondary battery 10, the positive electrode 1 and the negative electrode 2 are opposed to each other through the electrolyte layer 3. The positive electrode 1 is composed of a positive electrode active material 1a having a predetermined amount of a layered crystal structure and a base 1b that functions as a current collector. As shown in FIG. 10, a layer of the positive electrode active material 1a is provided on the surface of the base 1b.

  Similarly, the negative electrode 2 includes a negative electrode active material 2a and a base 2b as a current collector, and a layer of the negative electrode active material 2a is provided on the surface of the base 2b. The positive electrode 1 and the negative electrode 2 are opposed to each other with the electrolyte layer 3 interposed therebetween.

  Next, the present invention described in the above embodiment will be described in more detail in the following examples.

(Example 1)
In the synthesis of the active material for the positive electrode material, first, in step S100 shown in FIG. 3, 2 g of vanadium oxide (V ₂ O ₅ ), 0.3 g of a half molar amount of lithium sulfide (Li ₂ S) and 3,4-ethylene are used. Suspend 0.3 g of dioxythiophene (EDOT) in 50 ml of water. The suspension was heated to reflux for 12 hours.

Thereafter, in step S200, the refluxed suspension was refluxed, and a spray drying method using a four-fluid nozzle was applied in a drying atmosphere at a temperature of 130 ° C. By applying the spray drying method, fine powder particles of a black dry solid were obtained. When the particle size distribution of such a black powder was measured with a laser diffraction / scattering particle size distribution meter, it was found that it had a fine particle size in the range of about 0.2 μm to about 5 μm, as shown in FIG. D ₅₀ = 0.84 μm.

  Further, as shown in FIG. 4 described above, it was confirmed that the particles were spherical particles by a scanning electron microscope. Furthermore, when the obtained black powder was observed with a transmission electron microscope, it was confirmed that 99% of the aggregate of fine crystal grains having a layered structure with a layer length of 5 nm or more and 25 nm or less was obtained in area ratio. It was done.

  Further, when X-ray crystal diffraction of such fine powder particles, a peak was observed in the vicinity of 2θ = 10 ° as shown by a in FIG. Incidentally, it was also confirmed that when such fine powder particles were vacuum-dried at 250 ° C. for 12 hours, the crystal grains exceeded 30 nm as shown in FIG.

  The positive electrode material powder made of the black fine powder active material thus produced was used to form a positive electrode, and the possibility of using the active material as a positive electrode material was examined. That is, such a black fine powder material was mixed with 7% by weight of conductive carbon black and 5% by weight of a binder containing PVDF, and slurried using N-methylpyrrolidone (NMP) as a solvent. Thereafter, the slurry was coated on a conductive substrate Al foil used as a current collector by a doctor blade method to produce a positive electrode.

The electrode density of the prepared positive electrode was 1.4 g / cm ³ (g / cc). Using a positive electrode having such an electrode density, using a carbon negative electrode preloaded with lithium ions, using 1M LiBF ₄ dissolved in a mixed solvent of EC: DEC = 1: 3 as an electrolyte, a lithium secondary I assembled the battery. The result of subjecting this lithium secondary battery to charge / discharge evaluation at 0.1 C discharge is shown by the solid line in Example 1 of FIG.

(Example 2)
In this example, the active material for the positive electrode material was configured using lithium hydroxide instead of lithium sulfide of Example 1 above. That is, 2 g of vanadium oxide (V ₂ O ₅ ), 0.1 g of a half molar amount of lithium hydroxide (LiOH) and 0.3 g of 3,4-ethylenedioxythiophene (EDOT) are suspended in 50 ml of water. After the suspension was prepared, positive electrode material powder was produced in the same manner as in Example 1 according to the flowchart shown in FIG.

  Thus, in Example 2 as well as Example 1, a black fine powder that can be used as the positive electrode material was obtained. Such fine powder is not particularly shown in the figure, but has the same spherical particles as in FIG. 4, has the same particle size distribution as in FIG. 5, and has a structure as shown in FIG. It was confirmed to be a crystal grain. Furthermore, when the obtained black powder was observed with a transmission electron microscope, it was confirmed that 99% of aggregates of fine crystal grains having a layered structure with a layer length of 5 nm or more and 25 nm or less were obtained in area ratio. It was done.

A positive electrode material powder composed of such black fine powder was used to form a positive electrode. Formation of the positive electrode was performed in the same manner as in Example 1, and a lithium secondary battery was assembled using a carbon negative electrode on which lithium ions were previously supported, and charge / discharge evaluation was performed at 0.1 C discharge. Incidentally, the electrode density was 1.4 g / cm ³ (g / cc). The result is shown by the broken line in Example 2 in FIG.

(Example 3)
In this example, the active material for the positive electrode material was configured by changing the concentration of the synthesis solution in Example 1. That is, 2 g of vanadium oxide (V ₂ O ₅ ), 0.3 g of a half molar amount of lithium sulfide (Li ₂ S) and 0.3 g of 3,4-ethylenedioxythiophene (EDOT) are suspended in 25 ml of water. The suspension was heated to reflux for 12 hours.

Thereafter, in step S200 shown in FIG. 3, the spray drying method was applied to the refluxed suspension. By applying the spray drying method, fine powder particles of a black dry solid were obtained. When the particle size distribution of the black powder was measured with a laser diffraction / scattering particle size distribution meter, as shown in FIG. 13, D ₅₀ = 19.6 μm. The result of having produced a positive electrode similarly using this powder and having performed charging / discharging evaluation is shown in FIG. The electrode density of the produced positive electrode was 1.3 g / cm ³ (g / cc).

Example 4
In this example, the active material for the positive electrode material was configured by changing the concentration of the synthesis solution in Example 1. That is, 2 g of vanadium oxide (V ₂ O ₅ ), 0.3 g of a half molar amount of lithium sulfide (Li ₂ S) and 0.3 g of 3,4-ethylenedioxythiophene (EDOT) are suspended in 100 ml of water. The suspension was heated to reflux for 12 hours.

Thereafter, in step S200 shown in FIG. 3, the spray drying method was applied to the refluxed suspension. By applying the spray drying method, fine powder particles of a black dry solid were obtained. When the particle size distribution of the black powder was similarly measured with a laser diffraction / scattering particle size distribution analyzer, D ₅₀ = 0.1 μm. The result of having produced a positive electrode similarly using this powder and having performed charging / discharging evaluation is shown in FIG. The electrode density of the produced positive electrode was 1.5 g / cm ³ (g / cc).

(Comparative Example 1)
In Comparative Example 1, as in Example 1, as shown in FIG. 6, synthesis of an active material for the positive electrode material was performed in step S100 with 2 g of vanadium oxide (V ₂ O ₅ ) and a half molar amount of lithium sulfide ( Li ₂ S) 0.3 g and 3,4-ethylenedioxythiophene (EDOT) 0.3 g were suspended in 50 ml of water and synthesized.

In step S300, the suspension was concentrated and dried and solidified under reduced pressure concentration conditions of 75 ° C. and 10.67 kPa. Then, it grind | pulverized with the dry-type ball mill for 20 minutes by step S400. The particle size distribution of the active material obtained by such mechanical pulverization was in the range of about 3 μm to about 50 μm, as shown in FIG. D ₅₀ = 22 μm. It can be seen that it is about an order of magnitude larger than that of the first embodiment to which the present invention is applied.

  Then, the fine powder of black was obtained through the sieving of step S500 and the drying process of step S600. When the black fine powder thus obtained was observed with a scanning electron microscope, it was found that the result was non-spherical as shown in FIG.

  Using a positive electrode material powder made of such a black fine powdery active material, 7% by weight of conductive carbon black and 5% by weight of a binder containing PVDF are mixed, and a slurry using N-methylpyrrolidone (NMP) as a solvent is mixed. I made it. This slurry was coated on the Al foil of the current collector by the doctor blade method to produce a positive electrode.

The electrode density of the prepared positive electrode was 1.2 g / cm ³ (g / cc). Example 1 Using a positive electrode having such an electrode density, using a carbon negative electrode preliminarily supported with lithium ions, using 1M LiBF ₄ dissolved in a mixed solvent of EC: DEC = 1: 3 as an electrolytic solution. In the same manner, a lithium secondary battery was assembled. The lithium secondary battery was evaluated for charge and discharge at 0.1 C and 0.2 C discharges.

  Such evaluation is shown in FIG. 14 together with the results of Examples 1 to 4 as discharge capacity. As shown in FIG. 14, the discharge capacity (Wh / kg-active material) is about 14% lower than that of Example 1 in Comparative Example 1 in the case of 0.1C, and in Example of Comparative Example 2 in the case of 0.2C. It was confirmed that the active material produced by the production method of the present invention was superior to the positive electrode material. FIG. 15 also shows Example 1 and Comparative Example 1 together with respect to the initial discharge characteristics.

(Comparative Example 2)
In Comparative Example 2, the pulverization time is extended from 20 minutes to 1 hour in Step S400 of FIG. 6 in the manufacturing process of the positive electrode material of Comparative Example 1, thereby further pulverizing. However, it has been confirmed that the crystal structure is changed by lengthening the mechanical pulverization step. For example, as shown in FIG. In FIG. 16, the result by the X-ray diffraction of lithium vanadate is also shown as a reference.

  Since the active material of the electrode material that can be used as the positive electrode material to which the manufacturing method of the present invention is applied is preferably partially amorphousized, the amorphous material can be obtained by extending the pulverization step as in Comparative Example 2. It has been found that the active material produced at such a temperature of 250 ° C. or higher cannot be used characteristically.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments and examples. However, the present invention is not limited to the above-described embodiments and examples, and does not depart from the spirit of the invention. It goes without saying that various changes can be made.

  The present invention can be used particularly effectively in the field of positive electrode materials for lithium secondary batteries.

It is explanatory drawing which showed typically the layered crystal structure with a short layer length of this invention. It is explanatory drawing which showed typically the layered crystal structure with a long layer length different from this invention. It is a flowchart which shows the manufacturing method which is one embodiment of this invention. It is a drawing substitute photograph with the scanning electron microscope of the positive electrode material manufactured with the manufacturing method of one embodiment of this invention. It is explanatory drawing which shows the particle size distribution of the positive electrode material manufactured with the manufacturing method of one embodiment of this invention. It is a flowchart which shows the manufacturing method of the positive electrode material which has a mechanical grinding | pulverization process. It is explanatory drawing which shows the particle size distribution of the positive electrode material manufactured with the manufacturing method which has a mechanical crushing process. It is a drawing substitute photograph of the positive electrode material pulverized by the mechanical pulverization process using a scanning electron microscope. It is a flowchart which shows the manufacturing method of the positive electrode material of a prior art example. 1 is a cross-sectional view showing a schematic configuration of a non-aqueous lithium secondary battery to which the present invention can be applied. It is explanatory drawing which shows the result of the X-ray diffraction of the positive electrode material manufactured by the manufacturing method of this invention, and the positive electrode material at the time of vacuum-drying further at 250 degreeC. It is explanatory drawing which shows the charging / discharging characteristic of the Example in this invention. It is explanatory drawing which shows the particle size distribution of the positive electrode material manufactured with the manufacturing method of one Example in this invention. It is explanatory drawing which shows the comparison of the discharge capacity of the Example in this invention, and a comparative example with a table form. It is explanatory drawing which showed the initial stage discharge characteristic of the Example in this invention, and a comparative example. It is explanatory drawing which shows the crystal structure which changed when the grinding | pulverization process time in the conventional manufacturing method was extended.

Explanation of symbols

10 Nonaqueous lithium secondary battery 1 Positive electrode 1a Positive electrode active material 1b Base (current collector)
2 Negative electrode 2a Negative electrode active material 2b Substrate (current collector)
3 Electrolyte layer
L1 layer length
L2 layer length

Claims (12)

A method for producing an electrode material,
Without using a pulverization step of pulverizing large particles into small particles in a suspension having an oxide of at least one metal element selected from Group V elements and Group VI elements of the periodic table and a lithium compound, An electrode material is produced by applying a spray drying method. A method for producing an electrode material,
An electrode material by applying a spray drying method to a suspension having an oxide of at least one metal element selected from Group V and Group VI elements of the periodic table, a lithium compound, and a sulfur-containing organic substance A method for producing an electrode material, characterized by comprising: In the manufacturing method of the electrode material of Claim 1 or 2,
The method for producing an electrode material, wherein the metal element oxide is vanadium oxide. An electrode material having vanadium oxide doped with lithium ions,
An electrode material characterized by being water-soluble having an average particle size (D ₅₀ ) of 0.1 μm or more and 20 μm or less. The electrode material according to claim 4, wherein
The electrode material characterized in that the vanadium oxide has a layered crystal state in which fine crystal grains do not contain 0 and have a layer length of 30 nm or less. The electrode material according to claim 4 or 5,
The vanadium oxide is a material in which the layered crystalline state is partially amorphized so that a fine crystal having a layer length of 30 nm or less not including 0 is included in the layered crystalline material. . The electrode material according to claim 6,
The partial amorphization means an electrode material characterized in that an amorphous state and a layered crystal state of fine crystal grains having a layer length of 30 nm or less not containing 0 are mixed. The electrode material according to any one of claims 5 to 7,
The electrode material characterized in that in the layered crystal state in which the fine crystal grains have a layer length of 1 nm or more and 30 nm or less, the area ratio of the fine crystal grains observed in the cross section of the layered crystal substance is 30% or more. The electrode material according to any one of claims 5 to 8,
The electrode material, wherein the layered crystal state is at a temperature of 250 ° C. or higher and the fine crystal grains exceed 30 nm. The electrode material according to any one of claims 1 to 9,
An electrode material, wherein an electrode density of a positive electrode using the electrode material is 1.3 g / cm ³ or more and 2.5 g / cm ³ or less. In the electrode material according to any one of claims 4 to 10,
The vanadium oxide is heated in the presence of a sulfur-containing conductive polymer and a water-soluble lithium ion source,
The heated vanadium oxide is an electrode material characterized in that the diffraction angle 2θ of the X-ray diffraction pattern has a peak in a range of 5 to 15 ° and is a spherical particle. A non-aqueous lithium secondary battery comprising a positive electrode, a negative electrode, and a non-aqueous electrolyte layer disposed between the positive electrode and the negative electrode,
The non-aqueous lithium secondary battery, wherein the positive electrode has the electrode material layer according to any one of claims 4 to 11 formed on a conductive substrate.