WO2005082783A1

WO2005082783A1 - Lithium-containing iron oxyhydroxide and method for producing nonaqueous electrolyte electrochemical cell containing same

Info

Publication number: WO2005082783A1
Application number: PCT/JP2005/003685
Authority: WO
Inventors: Miki Yasutomi; Toru Tabuchi
Original assignee: Japan Storage Battery Co., Ltd.
Priority date: 2004-03-01
Filing date: 2005-02-25
Publication date: 2005-09-09

Abstract

A method for producing a lithium-containing iron oxyhydroxide is characterized in that a complex solution wherein metal lithium and a polycyclic aromatic compound are dissolved in a solvent is brought into contact with iron oxyhydroxide so that lithium is absorbed in iron oxyhydroxide. Also disclosed is a method for producing a nonaqueous electrolyte electrochemical cell using an electrode containing a lithium-containing iron oxyhydroxide obtained by such a method. By this method, there can be obtained a nonaqueous electrolyte secondary battery having a large discharge capacity and good cycle performance.

Description

Description Lithium-containing iron oxyhydroxide and method for producing nonaqueous electrolyte electrochemical cell containing the same

The present invention relates to a method for producing a lithium-containing iron oxyhydroxide and a nonaqueous electrolyte electrochemical cell containing the same. Background art

In recent years, small and lightweight lithium-ion secondary batteries have been widely used as power sources for electronic devices such as mobile phones and digital cameras. The multifunctionality of such electronic devices is remarkably progressing, and the emergence of batteries having a high energy density in place of the currently used lithium ion secondary batteries is expected. To that end, it is necessary to develop large-capacity positive and negative electrode active materials. As a cathode active material for its large capacity, such as Mn0 ₂ and V ₂ 0 ₅ is consider. However, at the stage of synthesizing these active materials, lithium that contributes to the redox reaction was not included. Therefore, the negative electrode active material combined with this was limited to metallic lithium and lithium alloy. However, electrodes using these metallic lithium-lithium alloys could not be used due to poor thermal stability and cycle performance.

On the other hand, when using a carbon negative electrode of a conventional lithium-ion batteries, the Mn0 ₂ and V ₂ 0 ₅ of the positive electrode active material had to be containing lithium. As a method therefor, there is a conventional electrochemical method in which a force electrode is applied to electrodes using these active materials in a lithium ion-containing electrolyte using a counter electrode such as lithium metal. However, there is a problem that an electrochemical control device is required and the manufacturing process becomes complicated. In addition to these, there are mainly the following four lithium doping methods. First, lithium butyl lithium containing material such as LiCoO ₂ and LiNi0 _2, phenylalanine lithium, naphthyl lithium, there have the _{_{Li x Co0 2 (χ> 1}} ) was immersed in a solution including lithium iodide and Li _x Ni0 There is a method of synthesizing ₂ (日本の> 1), which is described in Japanese Patent Application Laid-Open No. 05-135760. Next, there is a method in which a lithium-containing substance is immersed in a solution in which lithium ions and a polycyclic aromatic compound are dissolved to compensate for the irreversible capacity of the positive electrode, which is described in Japanese Patent Publication No. 3227771. There is also a method in which nickel oxyhydroxide and its derivatives are reacted in an organic solvent containing n-butyllithium. It is described in. Furthermore, also, there is way to dope the lithium Okishi nickel hydroxide, to utilize reduced function of the lithium naphthalene organic錯溶solution is described in the 44th Battery Symposium Abusu tractor preparative No. 1C0 ⁹ (2003) ing. In this case, a large capacity of 1000 mAh g ^-1 is obtained with a potential of 0.6 to 2.4 V vs. Li I Li + for the negative electrode, but a discharge capacity of about 90 mAh g- ^{1 for} the positive electrode Is only obtained. On the other hand, apart from the above-mentioned positive electrode active materials, iron-based active materials, which are inexpensive and have low environmental impact, have recently attracted attention. the been proposed LiFeP0 ₄ different olivine structure, there is reported an example of such Japanese Patent 9-134724 Patent Publication and Japan's patent publication 3,484,003. However, as reported in the Journal of Power Sources 81-81, 221 (1999), iron oxyhydroxide was newly discovered as the same iron-based material, but lithium, which contributes to the redox reaction, was not found. Since it is not included, a lithium ion battery using carbon for the negative electrode could not be obtained. Moreover, since the structure has a tunnel structure different from that of the conventional one, there is no idea to include lithium in this material, and is the above-mentioned method applied to other active materials applicable? Could not be foreseen at all. Disclosure of the invention

An object of the present invention is to provide a novel method for producing lithium in lithium-containing oxyiron hydroxide having a large capacity. Another object of the present invention is to provide a method for manufacturing a non-aqueous electrolyte electrochemical cell using the lithium-containing oxyiron hydroxide.

A first invention provides a method for producing lithium-containing iron oxyhydroxide, comprising: contacting a solution obtained by dissolving lithium metal and a polycyclic aromatic compound in a solvent with iron oxyhydroxide; In which lithium is absorbed.

According to a second invention, in the method for producing a lithium-containing oxyiron hydroxide according to the first invention, the polycyclic aromatic compound is at least one of naphthalene, phenanthrene, and anthracene. Things.

According to a third invention, in the method for producing lithium-containing oxyhydroxide of the first invention, the amount X of lithium stored in 1 mol of the oxyiron hydroxide is in the range of 0.5 mol ≤ X ≤ 2 mol. It is characterized by being within.

According to a fourth aspect, in the method for producing a lithium-containing oxyhydroxide of the first aspect, the oxyiron hydroxide is a J3 phase.

The fifth invention is directed to a method of manufacturing a nonaqueous electrolyte electrochemical cell, An electrode containing lithium-containing oxyiron hydroxide obtained by the method is used as a positive electrode.

A sixth invention is directed to a method for producing a nonaqueous electrolyte electrochemical cell, wherein the electrode containing lithium-containing oxyiron hydroxide obtained by the production method according to the second invention is used as a positive electrode. .

A seventh invention is a method for producing a nonaqueous electrolyte electrochemical cell, characterized in that the electrode containing lithium-containing oxyiron hydroxide obtained by the production method according to the third invention is used as a positive electrode. .

An eighth invention is directed to a method for producing a nonaqueous electrolyte electrochemical cell, wherein the electrode containing lithium-containing oxyiron hydroxide obtained by the production method according to the fourth invention is used as a positive electrode. .

A ninth invention is directed to a method for producing a nonaqueous electrolyte electrochemical cell, wherein the electrode containing lithium-containing oxyiron hydroxide obtained by the production method according to the first invention is used as a negative electrode. .

A tenth invention provides a method for producing a nonaqueous electrolyte electrochemical cell, characterized in that the electrode containing lithium-containing oxyiron hydroxide obtained by the production method according to the second invention is used as a negative electrode. is there. Brief Description of Drawings

FIG. 1 shows (a) FeOOH-Li _{lo 0} (b) FeOOH 'Li ₀ of the present invention. ₅ and (c) X-ray diffraction patterns of FeOOH.

FIG. 2 shows the electrochemical potential behavior of the lithium-containing oxyiron hydroxide electrode of Example 1.

FIG. 3 shows the electrochemical potential behavior of the iron oxyhydroxide electrode of Comparative Example 1.

FIG. 4 shows the electrochemical potential behavior of the electrode of Example 6.

FIG. 5 shows the electrochemical potential behavior of the electrode of Example 13.

FIG. 6 shows the charge / discharge characteristics of the non-aqueous electrolyte secondary battery of Example 14.

FIG. 7 shows the charge / discharge characteristics of the non-aqueous electrolyte secondary battery of Example 15. BEST MODE FOR CARRYING OUT THE INVENTION

As the polycyclic aromatic compound of the present invention, naphthalene, anthracene, phenanthrene methinolenaphthalene, ethinolenaphthalene, naphthacene, pentacene, pyrene, picene Use of trifluorene, anthanthrene, acenaphthene, acenaphthylene, benzopyrene, benzophnoleolene, benzophenanthrene, benzophnoleroacene, benzoperylene, coronene, chrysene, hexabenzoperylene or derivatives thereof. Can be.

In the oxyiron hydroxide of the present invention, a part of the iron is replaced with at least one element selected from Co, Ti, V, Cr, Mn, M, Cu and Zn.

(0 <a≤0.5, M is at least one selected from Co, Ti, V, Cr, Mn, Ni, Cu and Zn). These oxyiron hydroxides are prepared by adding Li, Na, K, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Pb and Sn in an aqueous solution in which iron salts are dissolved. The compound can be synthesized by adding a salt containing at least one element selected from the group consisting of and then hydrolyzing. The iron oxyhydroxide of the present invention can be used in any of the following phases.

The lithium-containing oxyhydroxide of the present invention is prepared by preparing a complex solution in which metallic lithium and a polycyclic aromatic compound are dissolved in an organic solvent, and contacting the complex solution with powder of oxyiron hydroxide. Can be obtained by Further, it can also be obtained by a method in which this complex solution is brought into contact with an electrode containing iron oxyhydroxide. It can also be obtained by contacting an organic solvent with oxyiron hydroxide or an electrode containing the same, and then dissolving lithium metal and the polycyclic aromatic compound in the solvent.

When lithium metal and a polycyclic aromatic compound are dissolved in an organic solvent, electrons are transferred from the lithium metal to the polycyclic aromatic compound, and anions and lithium ions are formed to form a complex solution. When all of the metallic lithium is dissolved, the complex solution contains lithium ions, polycyclic aromatic compound, polycyclic aromatic compound anion, and solvent. When only a part of metallic lithium is dissolved, the solution contains metallic lithium, lithium ion, polycyclic aromatic compound, anion of polycyclic aromatic compound, and solvent. Electrons are transferred from the anion of the polycyclic aromatic compound to the iron oxyhydroxide, and at the same time, lithium ions are absorbed into the iron oxyhydroxide. At this time, the polycyclic aromatic compound, ayuon, returns to the polycyclic aromatic compound, and thus has a catalytic role in the lithium storage reaction.

The concentration of lithium ions in this complex solution is preferably in the range from 0.07 g dm " ³ to saturation. If the concentration is less than 0.07 g dnf ³ , the occlusion time will be longer, and the occlusion time will be shorter. For this purpose, it is more preferable to make the lithium ion concentration saturated.

The concentration of the polycyclic aromatic compound in the complex solution is preferably from 0.005 to 2.0 mol dm- ³ . More favorable Mashiku is 0. 005~025 mol dnf ^3, more preferably 0. 005~0. 01 mol dnf ³ der The If the concentration of the polycyclic aromatic compound is less than 0.005 mol dm- ³ , the occlusion time is prolonged, and if the concentration is greater than 2.0 mol dm- ³ , the polycyclic aromatic compound precipitates in the solution.

The time for bringing the complex solution into contact with the oxyiron hydroxide is not particularly limited, but in order to occlude lithium sufficiently in the oxyhydroxide, 0.1 to 240 hours is preferable, and 0.1 to 72 hours. Time is more preferred. When the complex solution is contacted with iron oxyhydroxide, the lithium storage rate can be increased by stirring the solution. Also, by increasing the temperature of the solution, the occlusion rate can be increased. However, in order not to boil the solution, it is preferable that the temperature be equal to or lower than the boiling point of the solvent to be used. It is more preferable to set the range in consideration of workability.

Solvents used in the complex solution of the present invention include getyl ether, 1-methoxypropane, 1-methoxybutane, 2-methoxybutane, 1-methoxypentane, 2-methoxypentane, 1-methoxyhexane, 2-Methoxyhexane, 3-methoxyhexane, 1-ethoxypropane, 2-ethoxybutane, tetrahydrofuran, 2-methyltetrahydrofuran, 1,2-dimethyltetrahydrofuran, dimethylsulfoxide, etc. No. Thus, the type of the solvent used for the complex solution is not particularly limited. However, there is a problem that the substance generated by the decomposition of the solvent adheres to the surface of the iron oxyhydroxide. Alternatively, the decomposition product reacts with iron oxyhydroxide, causing a problem that the rate of insertion of lithium into the interior decreases. Therefore, as the solvent used for the complex solution, a chain-like monomer that is difficult to decompose is preferable.

The lithium-containing oxyhydroxide obtained by the production method of the present invention is obtained by storing X moles of lithium with respect to 1 mole of oxyhydroxide. The value of X can be controlled by the concentration of lithium ions and polycyclic aromatic compounds in the complex solution, reaction time, and temperature. The molar number X of lithium can be determined by the amount of charge of the electrode containing the obtained lithium-containing oxyiron hydroxide. The amount of charge electricity is defined as the electrode containing the lithium-containing oxyiron hydroxide as the working electrode, metallic lithium as the counter electrode and reference electrode, and ethylene carbonate (EC) and ethyl methyl carbonate (EMC) as the electrolyte. volume ratio of 1: used after dissolved 1 mol dm- ³ of LiC10 ₄ in a mixed solvent of 1, the 25 ° C, the theoretical capacity of the one-electron reaction of current 0. 01C mA (C is Okishi iron hydroxide Indicates the amount of electricity when charged to 4.2 V vs _D Li / Li + with a considerable constant current. Preferably, the value of x is 0.5≤x≤2. This is because in this range, the obtained electrode containing the lithium-containing oxyiron hydroxide exhibits excellent cycle performance. In the method of contacting the complex solution of the present invention with iron oxyhydroxide, the polycyclic aromatic compound functions as a catalyst for the reaction of storing lithium. In the course of the reaction, the polycyclic aromatic compound does not extract H from the iron oxide hydroxide. Therefore, since no by-product is generated, the desired lithium-containing iron oxyhydroxide can be obtained.

The crystal structure of the lithium-containing oxyiron hydroxide of the present invention is preferably amorphous. Here, the term “amorphous” refers to the case where the half-width of the peak at around 36.8 ± 0.5 ° of lithium-containing oxyiron hydroxide in X-ray diffraction using CuKa is 1.0 ° or more. FIG. 1 shows a typical X-ray diffraction pattern of the lithium-containing iron oxyhydroxide obtained by the production method of the present invention. In Fig. 1, (a) is FeOOH · Li _L. (B) FeOOH · Li. (C) of Fig. ₅ is the result of FeOOH. In Fig. 1, the symbol · indicates the peak of FeOOH in the α phase, the symbol port indicates the peak of the nickel substrate, and the symbol 〇 indicates the peak of polyethylene force. For the lithium-containing oxyhydroxide having an X value of 0.5, the half width was 1.0 ° or more. Therefore, it was found that when the value of X was 0.5 or more, the lithium-containing iron oxyhydroxide became amorphous. In addition, since no peaks other than iron oxyhydroxide, nickel on the substrate, and polyethylene cover were observed, it was found that no by-product was generated.

The lithium-containing oxyiron hydroxide of the present invention can be used for both positive and negative electrodes. When the lithium-containing oxyiron hydroxide of the present invention is used as a positive electrode active material of a non-aqueous electrolyte secondary battery, the negative electrode active material is not particularly limited. As the negative electrode active material, carbon materials such as graphite and amorphous carbon, oxides, nitrides, and the like can be used. Among these, carbon materials and oxides such as graphite and amorphous carbon are preferably used because of their excellent capacity / charge / discharge cycle performance. When the lithium-containing iron oxyhydroxide of the present invention is used as a negative electrode active material of a non-aqueous electrolyte secondary battery, the positive electrode active material is not particularly limited. For the positive electrode active material, transition metal compounds such as manganese dioxide and vanadium pentoxide, transition metal chalcogen compounds such as iron sulfide and titanium sulfide, and carbon materials such as activated carbon and graphite can be used.

Ethylene-propylene-diene terpolymer, acrylonitrile-butadiene rubber, fluororubber, polyacetate

, Polymethyl methacrylate, Polyethylene, Nitrocellulose, Polyvinylidene fluoride, Polyethylene, Polypropylene, Polytetrafluoroethylene, Tetrafluoroethylene-Hexafluoropropylene copolymer, Polyvinylidene monochloride Trifluoroethylene copolymer At least one selected from styrene-butadiene rubber (SBR) and carboxymethylcellulose (CMC) can be used. Either a non-aqueous solvent or an aqueous solution can be used as a solvent for mixing the binder. Non-aqueous solvents include N-methyl- ² -pyrrolidone, dimethyl'formamide, dimethylacetamide, methylethylketone, cyclohexanone, methyl acetate, methyl acrylate, getyltriamine, N-N-dimethylamino Propylamine, ethylene oxide, tetrahydrofuran and the like can be used. On the other hand, a dispersant, a thickener and the like can be added to the aqueous solution.

Iron, copper, stainless steel, nickel and aluminum can be used as current collectors for the electrodes. Further, as the shape, a sheet, a foam, a mesh, a porous expanded lattice, or the like can be used. Further, the current collector can be used with holes formed in any shape.

Organic solvents used for the electrolyte include ethylene carbonate, propylene carbonate, butylene carbonate, trifluoropropylene carbonate, γ-butyrolactone, sulfolane, 1,2-dimethoxetane, 1,2-jetoxetane, tetrahydrofuran, and tetrahydrofuran. Methyltetrahydrofuran, 3-methyl-1,3-dioxolane, methynole acetate, ethyl acetate, methyl propionate, ethyl ethyl propionate, dimethyl carbonate, methyl carbonate, ethyl methyl carbonate, dipropyl carbonate, methyl propyl carbonate, etc. Alternatively, they can be used in combination. In addition, carbonate compounds such as vinylene carbonate and butylene carbonate, benzene compounds such as biphenyl and cyclohexylbenzene, and sulfur compounds such as propane sultone can be used alone or in the electrolyte.

Further, the electrolyte solution and the solid electrolyte can be used in combination. As the solid electrolyte, a crystalline or amorphous inorganic solid electrolyte can be used. The _{former, Li l, Li 3 N,} Li 1 + x M x Ti 2 - x (P0 4) 3 (M = Al, Sc, Y, La), Li. . ₅ _ _3x R. _{_{. 5 + x Ti0 3 (R}} = La, Pr, Nd, Sm), or _{_{_{_{Li 4 _ x G ei - x}}}} P x S 4 to be able to use typified by Chio LISICON, the latter Li l-Li _₂ 0-B ₂ 0 ₅ system, Li _₂ 0- Si0 ₂ _{_{system, Lil- Li 2 S- B 2 S}} 3 type, Lil - Li _₂ S- SiS ₂ _{_{system, Li 2 S- SiS 2 - Li}} 3 P0 4 A system can be used.

Is a salt dissolved in an organic _{_{solvent, LiPF 6, LiC10 4, LiBF}} 4, LiAsF 6, LiPF (CF 3) 5, LiPF 2 (CF 3) 4, LiPF 3 (CF 3) 3, LiPF 4 (CF ₃ ) ₂ , LiPF ₅ (CF ₃ ), LiPF ₃ (C ₂ F ₅ ) ₃ , LiCF ₃ S0 ₃ , LiN (S0 ₂ CF ₃ ) ₂ , LiN (S0 ₂ CF ₂ CF ₃ ) ₂ , LiN (C0CF ₃₎ _{_{) 2, LiN (C0CF 2 CF}} 3) 2, LiC 4 B0 8 walking alone and can be used as a mixture. Among these, LiPF ₆ is preferable as the lithium salt because the cycle performance is improved. Furthermore, the concentration of these lithium salts is 0.5 to 2.0 range Moldnf ³ are preferred. Microporous membranes such as nylon, cellulose acetate, nitrocellulose, polysulfone, polyacrylonitrile, polyvinylidene fluoride and polyolefin can be used as separators in non-aqueous electrolyte electrochemical cells.

The shape of the nonaqueous electrolyte electrochemical cell is not particularly limited, and may be a square, an ellipse, a coin, a button, a sheet, or the like.

Example

Next, the present invention will be described in detail based on examples. However, the present invention is not limited by the following examples.

[Example 1]

4 mass of ferric sulfate. /. By adding 2% by mass of sodium hydroxide to the dissolved aqueous solution, _α- phase oxyiron hydroxide powder having an average particle size of 1.0 μm was synthesized. Next, a complex solution was prepared by dissolving naphthalene as a polycyclic aromatic compound having a concentration of 0.25 mol dnT ³ and a saturated amount of metallic lithium in geethylether as a solvent. Further, the oxyiron hydroxide powder was immersed in the complex solution, allowed to stand at 25 ° C. for 24 hours, filtered, and then washed with dimethyl carbonate. Finally, it was dried under reduced pressure at room temperature to obtain a lithium-containing oxyiron hydroxide powder according to the present invention as an active material.

80 mass of active material of this powder. /. 5% by mass of acetylene black and 15% by mass of polyvinylidene fluoride (PVDF) were mixed in N-methyl-2-pyrrolidone (banded P) to prepare a paste. The paste was applied on an aluminum foil having a thickness of 20 μια and dried at 70 ° C under reduced pressure to evaporate NMP. This was pressurized by a roller, and then slitted to a size of 10 mmW × 20 mmL × 100 μηιΤ to produce an electrode containing lithium-containing oxyhydroxide according to the present invention.

Then, this electrode as a working electrode, a metal lithium plate as the reference electrode contact Yopi counter, electrolytic EC and EMC and O volume ratio as solution 1: dissolve the LiC10 ₄ of 1 mol DNF ³ in a mixed solvent of 1 A three-electrode glass cell was fabricated using the above. The electrochemical potential behavior of this electrode was investigated as follows. At 25 ° C, the battery was charged to 4.2 V vs. Li / Li ⁺ with a current of 0.01 CmA, and then discharged to 1.5 V vs. Li / Li +. FIG. 2 shows the electrochemical potential behavior of this lithium-containing oxyiron hydroxide electrode. The potential of this electrode gradually shifted from 1.0 V vs. Li / Li ⁺ to 4.2 V vs. Li / Li ⁺ . This is probably because lithium was electrochemically desorbed from lithium-containing iron oxyhydroxide by charging. It was found that a large value of 307 mAh g " ¹ was obtained per unit mass of lithium-containing iron oxyhydroxide, and that the potential of the electrode during discharging was 4.2 V vs. Li I Li ⁺ Slowly shifted from 1.5 V to 1.5 V vs. Li I Li ⁺ , and the quantity of electricity (discharge capacity) was per unit mass of lithium-containing iron oxyhydroxide. A large capacity of 280 mAh g- ¹ was obtained. This value was 93% of the theoretical capacity when 1 mol of Li was inserted into iron oxyhydroxide. Therefore, by a simple method according to the present invention in which a solution in which lithium metal and a polycyclic aromatic compound are dissolved in a solvent is brought into contact with iron oxyhydroxide, lithium is absorbed in iron oxyhydroxide. It was found that a large real capacity close to the capacity could be obtained. As a reference example to prove the difficulty of the idea itself of the present invention, in Example 1, 1.0 μηι α phase was used. An electrode was prepared using a conventionally known 10 μm layered nickel oxyhydroxide instead of iron oxyhydroxide, and the electrochemical behavior was examined by applying the method of the present invention. The effect was investigated. As a result, the values of the charge electricity and the discharge capacity of the obtained lithium-containing nickel oxyhydroxide electrode are the values described in the 44th Battery Symposium on Abstract No. 1C09 (2003), respectively. Since it was as small as 104 mAh g- ¹ and 96 mAh g- ^1, which are almost the same as above, it can not be foreseen that from this cited example, it is possible to obtain an actual capacity comparable to the theoretical capacity as in the present invention. Thus, in the case of nickel oxyhydroxide, the same effect as in the case of iron oxyhydroxide of the present invention cannot be obtained because the crystal structure of nickel oxyhydroxide is a layered structure. It is presumed that when lithium is introduced, the layers are easily opened, so that even the solvent of the complex solution is taken into the layers and the electrochemical activity is reduced. On the other hand, since the iron oxide hydroxide has a tunnel structure, it is presumed that lithium-containing iron oxide hydroxide could be produced without taking the solvent of the complex solution into the interlayer. Therefore, from another point of view, it can be said that the method of the present invention exerts a great effect particularly by using oxyiron hydroxide. Operating voltage of the lithium-containing Okijiokishi nickel hydroxide / C based lithium ion batteries compared to 3V, LiFeP0 ₄ / C system 3. 5 V lithium ion batteries, is 2 V and a low operating voltage system as in the present invention Lithium-containing oxyhydroxide / iron / C-based lithium-ion batteries practically require large capacities close to the theoretical capacities, so the effect of the present invention can be said to be remarkable.

[Comparative Example 1]

A paste was prepared by mixing 80% by mass of the active material of the α-phase iron oxyhydroxide powder used in Example 1, 5% by mass of acetylene black, and 15% by mass of PVDF in a glass plate. This paste was applied on a 20-m-thick aluminum foil and dried under reduced pressure at 70. To evaporate the bandits P. This was pressurized with a roller, and then the size was adjusted to 10 mm WX 20 mmL X 100 μmT with a slitter to produce an electrode. The electrochemical potential behavior of this electrode was measured as follows. The electrode as a working electrode, a metallic lithium plate as a reference electrode Contact Yopi counter, the volume ratio of EC and EMC as the electrolytic solution 1: obtained by dissolving a LiC10 ₄ of 1 mol DNF ³ in a mixed solvent of 1 A three-electrode glass cell was fabricated using this method. The electrochemical potential behavior of this electrode was examined as follows. 4. At 25 ° C, current 0.01 C mA. After charging to 2 V vs. Li I Li ⁺ , the battery was discharged to 1.5 V vs. Li / Li +. Figure 3 shows the electrochemical potential behavior of this oxyiron hydroxide electrode. Charging characteristics do not appear in the figure, the potential was immediately ^4. Reached 2 V vs. Li I Li ^+. That is, the charged amount of electricity of this electrode was 0 niAh g- ¹ per unit mass of iron oxyhydroxide. The reason for this is that the electrochemical iron elimination reaction did not progress because the iron oxide hydroxide electrode did not contain lithium. In the discharge, the potential of this electrode gradually shifted from 3.2 V vs. Li I Li + to 1.5 V vs. Li / Li ⁺ . This electric quantity (discharge capacity) was 281 mAh per unit mass of iron oxyhydroxide.

Here, important findings were found. That is, lithium-containing oxyhydroxide prepared by a method in which conventional iron oxyhydroxide is brought into contact with a solution containing lithium metal and a polycyclic aromatic compound can be chemically synthesized and contained. That is, the electrode has a large charge amount and a large discharge capacity. The amount of charge of the lithium-containing oxyiron hydroxide electrode of 307 mAh g— ¹ means that _x represented by the general formula Fe00H ′ Li x is a value of 1.

[Comparative Example 2]

Instead of the complex solution used in Example 1, a 1.6 mol dm- ³ n-butyllithium Jetyl ether solution was used, and a-phase oxyiron hydroxide powder was immersed in this solution. For 24 hours, filtered, and washed with dimethyl carbonate. This was dried under reduced pressure at room temperature to obtain a powder. The powder 80 wt%, and 5 wt% of acetylene black, polyvinylidene fluoride (PVDF) 15 weight ^_0/0 and the N- methyl - 2 - were mixed in pyrrolidone (丽P), the pace preparative Produced. The NMP was evaporated by applying this paste on an aluminum foil having a thickness of 20 μπι and drying under reduced pressure at 70 ° C. This was pressurized with a roller, and then sized to 10 mmW × 20 mmL × 100 jumT with a slitter to produce an electrode.

Then, this electrode as a working electrode, a metal lithium plate as the reference electrode contact Yopi counter, electrolytic volume ratio of EC and EMC as solution 1: dissolve LiC10 ₄ of 1 mol dm- ³ in a mixed solvent of 1 A three-electrode glass cell was fabricated using the resulting material. The electrochemical potential behavior of this electrode was investigated as follows. At 25 ° C, charge up to 4.2 V vs. Li / Li ⁺ with a current of 0.01 C mA After charging, the battery was discharged to 1.5 V vs. Li I Li ⁺ . The charge and discharge capacity of the electrode in the first cycle were small, 72 mAh g- ¹ and 65 mAh, respectively. The reason is considered to be that when n-butyllithium getyl ether solution was used, H was extracted from the oxyhydroxide and the crystal structure collapsed, and by-products such as iron oxide were generated. .

Note that instead of n-butyllithium used in Comparative Example 2, s-butyllithium, t-butyllithium, phenyllithium, lithium iodide, or lithium borohydride was used and lithium-containing oxyiron hydroxide was used. Even in the case of the production, as in Comparative Example 2, by-products such as iron oxide were generated.

From this, it was found that it was important to use a complex solution containing iron oxyhydroxide, metallic lithium and a polycyclic aromatic compound, and that a great effect could be obtained.

[Example 2]

In Example 1, the immersion time was changed to 30 minutes to obtain a lithium-containing oxyhydroxide powder according to the present invention. In Example 1, an electrode B containing lithium-containing iron oxyhydroxide according to the present invention was obtained using the lithium-containing iron oxyhydroxide powder as an active material.

[Example 3]

In Example 1, the immersion time was changed to 1 hour to obtain a lithium-containing iron oxyhydroxide powder according to the present invention. In Example 1, an electrode C containing lithium-containing iron oxyhydroxide according to the present invention was obtained by using the lithium-containing iron oxyhydroxide powder as an active material.

[Example 4]

In Example 1, the immersion time was set to 48 hours to obtain a lithium-containing oxyiron hydroxide powder according to the present invention. In Example 1, an electrode D containing the lithium-containing iron oxyhydroxide according to the present invention was obtained by using the lithium-containing iron oxyhydroxide powder as an active material.

[Example 5]

In Example 1, the immersion time was set to 60 hours to obtain a lithium-containing oxyiron hydroxide powder according to the present invention. The electrode E containing lithium-containing iron oxyhydroxide according to the present invention was obtained using the lithium-containing iron oxyhydroxide powder as the active material in Example 1.

Electrodes B, D and E containing these lithium-containing oxyiron hydroxides were examined for their electrochemical potential behavior as follows. The lithium-containing iron oxyhydroxide electrode obtained as the working electrode, a metal lithium plate as the reference electrode and the counter electrode, and 1 mol dnf ^{3 in a} 1: 1 mixed solvent of EC and EMC as the electrolyte solution. It used after dissolved LiC10 ₄ of 3 Gokukashoku shone ιϊ 1ϊ 1ϊ! Ί We have manufactured a glass cell. 4.2 V vs. Li / Li + at 25 ° C at 0.01 C mA

After charging to BDE c, the battery was discharged to 1.5 V vs. Li I Li + for 10 cycles. And determining the value of X in the lithium-containing Okishi iron hydroxide represented by the general formula FE00H 'Li _x from charge electricity quantity. Table 1 summarizes the charge amount and discharge capacity of the obtained electrode containing lithium-containing iron oxyhydroxide in the first cycle. The ratio of the discharge capacity at the 10th cycle to the discharge capacity at the 1st cycle is defined as “discharge capacity retention rate /%”. The electrode discharge capacity retention ratio / of the electrode containing lithium-containing oxyiron hydroxide obtained in Example 1. /. Table 1 also shows the measurement results.

table 1

--Lithium-containing oxyhydroxide 1st cycle 1st cycle Discharge capacity

X value of iron Discharge capacity of charged electricity Retention rate

From Table 1, when the value of x of the lithium-containing oxyiron hydroxide represented by the general formula Fe00H 'Li _x is 0.5≤x≤2.0, the discharge capacity retention rate of the electrode using it is It was found to be more than 80%, indicating better charge / discharge cycle performance. Therefore, it is preferable that the value of X of the lithium-containing oxyhydroxide represented by the general formula Fe00H 'Li _x is 0.5≤χ≤2.0.

[Example 6]

In Example 1, the condition of standing for 24 hours was changed to stirring for 24 hours to obtain a lithium-containing oxyiron hydroxide powder according to the present invention. In Example 1, the electrode F containing the lithium-containing iron oxyhydroxide according to the present invention was obtained using the lithium-containing iron oxyhydroxide powder as the active material. The electrochemical potential behavior of this electrode was examined as follows. An electrode containing lithium-containing oxyhydroxide obtained as a working electrode, a metal lithium plate as a reference electrode and a counter electrode, and 1 mol in a mixed solvent of EC and EMC in a 1: 1 volume ratio of EC and EMC as an electrolyte. dm- ³ used after dissolved LiC10 ₄ of was fabricated glass cell three-electrode. At 25 ° C, the battery was charged to 4.2 V vs. Li / Li ⁺ with a current of 0.01 CmA, and then discharged to 0.3 V vs. Li / Li ⁺ . Figure 4 shows the electrochemical potential behavior of this electrode. The amount of electricity charged per unit mass of the lithium-containing oxyiron hydroxide obtained by this method was 1210 mAh g- ¹ . This means that X represented by the general formula Fe00H 'Li _x was inserted 4.0. Also, the discharge capacity is 1112 mA. It has been found that the lithium-containing oxyiron hydroxide of the present invention can be charged and discharged even in a low potential region and can be used as a negative electrode active material of a nonaqueous electrolyte electrochemical cell.

[Example 7]

In Example 1, the solvent of the complex solution was 1-methoxybutane, and a lithium-containing oxyiron hydroxide powder according to the present invention was obtained. An electrode G containing lithium-containing oxyiron hydroxide according to the present invention was obtained by using the lithium-containing oxyiron hydroxide powder as an active material in Example 1.

[Example 8]

In Example 1, the solvent of the complex solution was 1-methoxybutane, and the polycyclic aromatic compound was anthracene, whereby a lithium-containing oxyiron hydroxide powder according to the present invention was obtained. In Example 1, the electrode H containing the lithium-containing oxyhydroxide according to the present invention was obtained using the lithium-containing oxyhydroxide as the active material.

[Example 9]

In Example 1, lithium-containing oxyiron hydroxide powder according to the present invention was obtained using 1-methoxybutane as the solvent of the complex solution and phenanthrene as the polycyclic aromatic compound. In Example 1, an electrode I containing the lithium-containing oxyhydroxide according to the present invention was obtained using the lithium-containing oxyhydroxide as the active material.

[Example 10]

In Example 1, a lithium-containing iron oxyhydroxide powder according to the present invention was obtained by using 1-methoxypropane as a solvent for the complex solution. In Example 1, an electrode J containing the lithium-containing iron oxyhydroxide according to the present invention was obtained by using the lithium-containing iron oxyhydroxide powder as the active material.

[Example 11]

In Example 1, a lithium-containing oxyiron hydroxide powder according to the present invention was obtained using 1-methoxypropane as the solvent of the complex solution and anthracene as the polycyclic aromatic compound. In Example 1, an electrode κ containing lithium-containing iron oxyhydroxide according to the present invention was obtained using the lithium-containing iron oxyhydroxide powder as an active material.

[Example 12]

In Example 1, a lithium-containing oxyiron hydroxide powder according to the present invention was obtained using 1-methoxypropane as the solvent of the complex solution and phenanthrene as the polycyclic aromatic compound. In Example 1, the active material was the lithium-containing iron oxyhydroxide powder, Thus, an electrode L containing a solution-containing oxyiron hydroxide was obtained.

Pole pole pole pole pole

Electrodes G, H, I, J, K and L containing lithium-containing oxyiron hydroxide of GHKLJI et al. Were examined for electrochemical potential behavior as follows. A lithium-containing iron oxyhydroxide electrode obtained as a working electrode, a metal lithium plate as a reference electrode and a counter electrode, and an electrolyte of 1 mol dm in a mixed solvent of EC and EMC at a volume ratio of 1: 1. - used after dissolved LiC10 ₄ of ^3, were fabricated glass cell three-electrode. At 25 ° C, the battery was charged to 4.2 V vs. Li I Li ⁺ with a current of 0.01 C mA, and then discharged to 1.5 V vs. Li I Li +. Table 2 shows the values of the charge amount and the discharge capacity of the obtained electrode containing lithium-containing oxyiron hydroxide in the first cycle.

Table 2

Electrode solvent Polycyclic aromatic compound 1st cycle 1st cycle

Charging electricity discharging capacity

I mAh g-1 ¹ I mAh g- ¹

1-methoxyph, tan naphthalene 300 281

1-methoxyph, tan anthracene 301 273

1-methoxyph, tan fenanthrene 297 286

1-methoxyph. Loha. Naphthalene 296 272

1-methoxyv. Loha. Anthracene 295 267

1-methoxyv. Loha. Table 2 shows that even when the solvent of the complex solution of Example 1 and the type of the polycyclic aromatic compound were changed, about 300 mAhg- ¹ of charge electricity was obtained in the first cycle. This indicates that the general formula FE00H 'Li _x in the lithium-containing Okishi X of approximately 1 of the lithium-containing Okishi iron hydroxide value of iron hydroxide to be the table were obtained. This means that Fe00H-Li _x (0.5 ≤ X ≤ 2) can be produced even when the solvent of the complex solution of Example 1 and the type of polycyclic aromatic compound are changed. Therefore, naphthalene, phenanthrene and anthracene may be used as the polycyclic aromatic compound used for the complex solution.

[Example 13]

By adding 0.033 mol of lithium sulfate to an aqueous solution in which 0.1 mol of ferric chloride was dissolved, an oxyiron hydroxide powder having an average particle size of 1.0 μm was synthesized. This | 3-phase iron oxyhydroxide was immersed in the same complex solution as in Example 1, allowed to stand at 25 for 24 hours, filtered, and washed. This was dried under reduced pressure at room temperature to obtain a lithium-containing iron oxide hydroxide powder according to the present invention. In Example 1, an electrode containing the lithium-containing oxyhydroxide according to the present invention was obtained by using the lithium-containing oxyhydroxide powder as the active material. This electrode Was examined in the following manner. An electrode of lithium-containing iron oxyhydroxide obtained as a working electrode, a metal lithium plate as a reference electrode and a counter electrode, and 1 mol dm in a mixed solvent of EC and EMC in a 1: 1 volume ratio with an electrolyte. - used after dissolved LiCl0 ₄ of ^3, were fabricated glass cell three-electrode. At 25 ° C, the battery was charged to 4.2 V vs. Li / Li ⁺ with a current of 0.01 CmA, and then discharged to 1.5 V vs. Li / Li +. Figure 5 shows its electrochemical potential behavior. The amount of electricity charged per unit mass of the lithium-containing iron oxyhydroxide is 290 mAh g- ¹ . This means that _x represented by the general formula FeOOH 'Li _x was inserted by 0.9. The discharge capacity was 351 mAh g- ¹ . Therefore, it is preferable to use i3-phase iron oxyhydroxide powder.

[Example 14]

A non-aqueous electrolyte secondary battery (Fe00H'Li / C system) using the lithium-containing oxyhydroxide obtained in Example 1 as a positive electrode active material and graphite as a negative electrode active material was produced. The fabrication method is as follows. A paste was prepared by mixing 80% by mass of the lithium-containing oxyiron hydroxide powder obtained in Example 1, 5% by mass of acetylene black, and 15% by mass of PVDF in 丽 P. This paste was applied on an aluminum foil having a thickness of 20 μια and dried under reduced pressure at 70 ° C to evaporate NMP. This was pressurized with a roller, and then cut into a size of 10 mmW × 20 mmL × 100 μmT with a slitter to produce a positive electrode having a nominal capacity of 14.2 mAh. Next, 80 mass of flaky graphite with average particle size of 10 μm. /. And 20% by mass of PVDF were mixed in NMP to prepare a paste. This paste was applied on a 15-μm-thick copper foil and dried at 150 ° C to evaporate NMP. This was compression-molded by a roll press and cut into a size of 10 mmW x 20 mmL x 100 µmT with a slitter to produce a negative electrode with a nominal capacity of 18 mAh.

Using these positive electrodes Contact Yopi negative electrode, a volume ratio of EC and EMC as the electrolytic solution using a 1: obtained by dissolving a LiC10 ₄ of 1 mol dm- ³ in a mixed solvent of 1, nominal capacity 14. A 2 mAh flooded FeOOH'Li / C. Nonaqueous electrolyte secondary battery was fabricated.

This battery was charged and discharged at 25 ° C. with a constant current of 0.1 C mA. Figure 6 shows the charge / discharge characteristics. This battery is capable of charging and discharging, the charge electrical quantity Contact Yopi discharge capacity was respectively 1 1. 3 mAh and I ^5. 0 mAh. The charge / discharge reaction of this battery is considered as in the following equation (1). The right direction is the charging reaction, and the left direction is the discharging reaction.

FeOOH- Li + 6C = FeOOH + LiC ₆ (1)

From this, it was found that a new secondary battery can be manufactured according to the present invention. Therefore, the lithium-containing iron oxyhydroxide of the present invention is used as a positive electrode and contains no lithium. A non-aqueous electrolyte electrochemical cell can be formed by combining with a carbon material such as graphite or amorphous carbon, and an anode such as an oxide or a nitride.

[Example 15]

Vanadium pentoxide (V ₂ 0 ₅₎ as the positive electrode active material, to produce a nonaqueous electrolyte secondary battery using lithium-containing Okishi water iron oxide according to the present invention as a negative electrode active material (V ^ s / FeOOH 'Li system). The fabrication method is as follows. V ₂ 0 ₅ powder ⁷⁵ mass average particle diameter of 80 nm. /. And 5 mass of acetylene black. /. And PVDF20 mass ° /. And Paste were mixed in a corrupt P. The NMP was evaporated by applying this paste to aluminum foil ± with a thickness of 20 μπι and drying under reduced pressure at ΙδΟ ° C. This was pressurized by a roller, and then cut into a size of 10 mmW × 20 mmL × 100 / imT with a slitter to produce a positive electrode having a nominal capacity of 20 mAh. Further, 80% by mass of the lithium-containing iron oxyhydroxide powder obtained in Example 6 and 5% by mass of acetylene black. /. And, PVDF15 mass. /. And were mixed in NMP to make a paste. This base was applied on a 20-m-thick aluminum foil and dried at 70 ° C under reduced pressure to evaporate NMP. This was pressurized with a roller, and then cut into a size of 10 mmW × 20 mmL × 100 mT with a slitter to produce a negative electrode having a nominal capacity of 74 mAh.

With these positive and negative electrodes, the volume ratio of EC and EMC as the electrolytic solution using a 1: obtained by dissolving a LiC10 ₄ of 1 mol dm- ³ in a mixed solvent of 1 nominal capacity of Furaddeddo type 20 mAh

Li-based non-aqueous electrolyte secondary batteries were fabricated.

This battery was charged and discharged at a constant current of 0.1 C mA at 25 ° C. Fig. 7 shows the charge / discharge characteristics. This battery was chargeable and dischargeable, and the charged electricity and discharge capacity were 13.5 mAh and M. 7 mAh, respectively. The charge / discharge reaction of this battery is considered as in the following equation (2). The right direction is the charging reaction, and the left direction is the discharging reaction.

V ₂ 0 ₅ + l / 2Fe00H- Li ₄ = Li ₂ V ₂ 0 ₅ + l / 2Fe00H (2)

From this, it was found that a new secondary battery can be manufactured according to the present invention. Therefore, using the lithium-containing oxyhydroxide of the present invention as a negative electrode, a transition metal compound containing no lithium, such as manganese dioxide or vanadium pentoxide, or a transition metal chalcogen such as iron sulfide or titanium sulfide. A non-aqueous electrolyte electrochemical cell can be obtained by combining the compound and a positive electrode such as activated carbon or graphite.

This application is based on Japanese Patent Application (No. 2004-055705) filed on March 1, 2004, the contents of which are incorporated herein by reference.

Claims

The scope of the claims

1. In a method for producing lithium-containing iron oxyhydroxide, a solution in which lithium metal and a polycyclic aromatic compound are dissolved in a solvent is brought into contact with iron oxyhydroxide to absorb lithium into the iron oxyhydroxide. The method characterized by making it.

2. The process for producing lithium-containing iron oxyhydroxide according to claim 1, wherein the polycyclic aromatic compound is at least one of naphthalene, phenanthrene, and anthracene. .

3. The method for producing lithium-containing oxyhydroxide according to claim 1, wherein the amount X of lithium stored in 1 mol of the oxyiron hydroxide is within a range of 0.5 mol X ^ 2 mol. A method characterized by:

4. The method for producing lithium-containing iron oxyhydroxide according to claim 1, wherein the iron oxyhydroxide is a phase.

5. A method for producing a non-aqueous electrolyte electrochemical cell, characterized in that an electrode containing lithium-containing oxyiron hydroxide produced by the method according to claim 1 is used as a positive electrode.

6. The method for producing a non-aqueous electrolyte electrochemical cell according to claim 5, wherein the electrode including lithium-containing oxyiron hydroxide produced by the method according to claim 2 is used as a positive electrode. A method comprising:

7. The method for producing a non-aqueous electrolyte electrochemical cell according to claim 5, wherein the electrode containing lithium-containing oxyiron hydroxide produced by the method according to claim 3 is used as a positive electrode. A method comprising:

8. The method for producing a non-aqueous electrolyte electrochemical cell according to claim 5, wherein the electrode containing lithium-containing oxyiron hydroxide produced by the method according to claim 4 is referred to as a positive electrode. A method comprising:

9. A method for producing a nonaqueous electrolyte electrochemical cell, wherein an electrode containing lithium-containing oxyiron hydroxide produced by the method according to claim 1 is used as a negative electrode.

10. The method for producing a non-aqueous electrolyte electrochemical cell according to claim 9, wherein the electrode containing lithium-containing oxyiron hydroxide produced by the method according to claim 2 is a negative electrode. A method characterized in that: