JP2005317277A - Nonaqueous electrolyte battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new lithium-containing metal compound having excellent charging/discharging cycle property, charging voltage continuously changing in one step, and low cost, and to establish a condition for reaction and a composition optimum for synthesis, and to provide a nonaqueous electrolyte battery excellent in charging/discharging cycle property using the above compound as a cathode activator. <P>SOLUTION: The nonaqueous electrolyte battery having a cathode and an anode uses an oxide expressed by general formula (1); Li<SB>x</SB>H<SB>1-x</SB>Ni<SB>y</SB>Fe<SB>z</SB>M<SB>a</SB>O<SB>2</SB>, as a cathode activator, (wherein, M denotes one element chosen from Al, Zn, Ca, Sr, Nb, Mg, Cd, Cu, V, Cr, Mo, Ti, W, and Ag, 0<X/(Y+Z)≤1, 0.95≤Y+Z+a≤1.1, 0.025≤Z/(Y+Z)≤0.1, 0≤a≤0.05). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a non-aqueous electrolyte battery using a compound containing Li, Ni, Fe, O, and H as a positive electrode active material.

  In recent years, with the development of portable electronic devices such as mobile phones and video cameras, development of high-performance batteries is desired. Lithium ion secondary batteries using a lithium transition metal composite oxide for the positive electrode and graphite and amorphous carbon for the negative electrode are widely put into practical use as non-aqueous electrolyte secondary batteries having a high operating voltage and a high energy density.

  However, lithium transition metal oxides such as lithium cobaltate, which have been used as the positive electrode active material of conventional nonaqueous electrolyte secondary batteries, have limited discharge capacity, high cost, and safety. I have a lot of problems. Therefore, a high-capacity and inexpensive material is required as the positive electrode active material. As one of the novel positive electrode active materials, nickel oxyhydroxide having a high capacity has been proposed.

  However, nickel oxyhydroxide has poor charge / discharge cycle performance. Therefore, research and development have been actively attempted to improve the charge / discharge cycle performance by replacing nickel of nickel oxyhydroxide with elements such as Co, Zn, and Al.

In Patent Document 1, a hydroxide in which nickel element and manganese element are dissolved in 1: 1 by a coprecipitation method is prepared, and this hydroxide and lithium carbonate or lithium hydroxide are mixed at a temperature of 550 ° C. or higher. A rhombohedral LiNi _1/2 Mn _1/2 O ₂ obtained by firing is disclosed.

Patent Document 2 discloses that M (OH) ₂ (wherein M is at least one element selected from Co, Ni, and Mn) chemically or electrochemically in an aqueous solution containing a Li salt. A method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery is disclosed in which the average oxidation number of the element M is greater than 3 and less than or equal to 4 by oxidation.

Furthermore, in Patent Document 3, an alkaline aqueous solution containing Li, Ni, Co, Mn, Fe ions, etc. is oxidized using ozone as an oxidizing agent to produce lithium nickelate containing a small amount of Co, Mn, Fe. A low temperature direct oxidation method (100 ° C. or lower) is disclosed. The obtained lithium nickelate was 4 V to 1.5 Vvs. It can be charged / discharged in the range of Li / Li ⁺ and shows an initial discharge capacity of around 300 mAh / g. However, the discharge potential of this lithium nickelate was at least two stages, and the charge / discharge cycle performance was insufficient.

  Non-Patent Document 1 discloses a method for producing a lithium-containing nickel oxide at low temperature (100 ° C. or lower) and its charge / discharge characteristics. However, the discharge potential of this lithium-containing nickel oxide was also two steps, and the charge / discharge cycle performance was not sufficient.

  Furthermore, Non-Patent Document 2 discloses a synthesis method and electrochemical characteristics of nickel oxyhydroxide in which a part of Ni is substituted with Co or Zn. The initial discharge capacity of this nickel oxyhydroxide was about 200 mAh / g, but the charge / discharge cycle performance was inferior.

JP 2002-42813 A JP 2002-42813 A JP 2002-137923 A J. et al. Maruta, H.M. Yasuda, M .; Yamachi J. et al. Power Sources, 90, 89-94 (2000) H. Sasaki, H .; Yasuda, M .; Yamachi GSNews Technical Report, 60 (1), 12-16 (2001)

  As described in Patent Document 2, the change in the discharge voltage of nickel oxyhydroxide was continuous in the range of 4.2 to 1.5 V on the basis of lithium, but the charge / discharge cycle performance was inferior. Moreover, although the discharge capacity of the lithium-containing nickel oxide produced by the low-temperature direct oxidation method disclosed in Patent Document 3 is large, the discharge potential is in two stages. At present, nickel oxyhydroxide that can continuously discharge in the range of 4.2 to 1.5 V, has a high discharge capacity, and has excellent charge / discharge cycle performance has not been obtained.

  Therefore, in order to obtain nickel oxyhydroxide with one-stage discharge potential, large discharge capacity, and excellent charge / discharge cycle characteristics, optimization of the type and amount of element to replace nickel in nickel oxyhydroxide It is necessary to optimize reaction conditions such as starting materials and reaction temperature. At present, however, useful reaction conditions and means have not been established.

  Therefore, the object of the present invention is to propose a novel lithium-containing metal compound with excellent charge / discharge cycle performance, continuous discharge potential change in one step, and low cost, and to establish optimum reaction conditions and composition in the synthesis thereof. An object of the present invention is to provide a non-aqueous electrolyte battery excellent in charge / discharge cycle characteristics using a positive electrode active material.

The invention according to claim 1, in a non-aqueous electrolyte battery comprising the positive electrode and the negative electrode, the general formula _{Li x H 1-x Ni y} Fe z M a O 2 ( where, M is Al, Zn, Ca, Sr, Nb , Mg, Cd, Cu, V, Cr, Mo, Ti, W, Ag, at least one selected from the group consisting of 0 <X / (Y + Z) ≦ 1, 0.95 ≦ Y + Z + a ≦ 1.1, 0. An oxide represented by 025 ≦ Z / (Y + Z) ≦ 0.1, 0 ≦ a ≦ 0.05) is used as the positive electrode active material.

  According to a second aspect of the present invention, in the non-aqueous electrolyte battery, in an X-ray diffraction pattern using CuKα rays of the oxide, diffraction angles (2θ) of 18.6 ° ± 1 °, 38 ° ± 1 °, 43. It is characterized by showing diffraction peaks at 5 ° ± 1 ° and 64 ° ± 1 °.

  The invention of claim 3 is the method for producing a positive electrode active material for a non-aqueous electrolyte battery, wherein a plurality of compounds containing Li, Ni, Fe, M, O, and H are heated at a temperature of 100 ° C. or higher and 250 ° C. or lower. It is characterized by doing.

  The positive electrode active material for a nonaqueous electrolyte battery according to the present invention is a lithium-containing layered oxide containing Li, H, Ni, Fe, and M in which Ni atoms and Fe atoms are mixed at an atomic level. Then, by optimizing the molar content Z of Fe in the oxide, a positive electrode active material excellent in cost, discharge capacity, continuous potential change, and charge / discharge cycle performance can be obtained.

  Moreover, when the oxide as the positive electrode active material has a peak at a specific position in the X-ray diffraction pattern, a positive electrode active material that does not contain impurities and exhibits excellent characteristics can be obtained.

  Furthermore, the lithium-containing layered oxide containing Li, H, Ni, Fe, and M according to the present invention can be produced by heating at a medium to low temperature of 100 ° C. or more and 250 ° C. or less.

  The present invention relates to a lithium-containing metal compound used as a positive electrode active material of a nonaqueous electrolyte battery and a method for producing the same. Nonaqueous electrolyte batteries of the present invention include primary batteries and secondary batteries.

  The inventor has paid attention to a transition metal compound containing lithium as a positive electrode active material of a non-aqueous electrolyte battery, and has intensively studied various combinations of elements, mixing ratios thereof, and synthesis conditions.

As a result, the general formula _{Li x H 1-x Ni y} Fe z M a O 2 ( where, M is Al, Zn, Ca, Sr, Nb, Mg, Cd, Cu, V, Cr, Mo, Ti, W, At least one selected from the group consisting of Ag, 0 <X / (Y + Z) ≦ 1, 0.95 ≦ Y + Z + a ≦ 1.1, 0.025 ≦ Z / (Y + Z) ≦ 0.1, 0 ≦ a ≦ 0 .05) was used as a positive electrode active material.

The formula represented by _{Li x H 1-x Ni y} Fe z M a O 2, oxide containing Li, H, Ni, Fe and M, Fe a part of nickel of lithium-containing nickel oxide It was discovered that the charge / discharge capacity, the charge / discharge potential characteristics, and the charge / discharge cycle performance can be controlled by changing the Fe content.

  Furthermore, a part of nickel may be substituted with at least one selected from the group consisting of Al, Zn, Ca, Sr, Nb, Mg, Cd, Cu, V, Cr, Mo, Ti, W, and Ag. .

  In the oxide according to the present invention, the reason why 0 <X / (Y + Z) ≦ 1 is that an active material in a discharged state is obtained by producing a lithium layered oxide, but the lithium content is larger than 1. This is because the compound was not obtained. However, as the charge / discharge reaction proceeds, the value of (X / (Y + Z)) can vary between 0 and 2.

  The reason for satisfying 0.95 ≦ Y + Z + a ≦ 1.1 is that the atomic ratio between the transition metal and oxygen contained in the oxide of the present invention can be controlled in the vicinity of ½, and the present invention has a layered structure. It is because the oxide of this is obtained.

  The reason why 0.025 ≦ Z / (Y + Z) ≦ 0.1 is that when the value of Z / (Y + Z) is smaller than 0.025, the discharge curve of the oxide has two stages, and the object of the present invention If this value is larger than 0.1, Fe remains as an impurity without being completely replaced by Ni sites.

  The reason why 0 ≦ a ≦ 0.05 is effective in stabilizing the crystal structure when the oxide of the present invention contains a metal M other than Ni and Fe, and is within this range. This is because when it is larger than 05, the discharge capacity is reduced.

  Further, according to the present invention, in the X-ray diffraction pattern using CuKα ray of the oxide, the diffraction angle (2θ) is 18.6 ° ± 1 °, 38 ° ± 1 °, 43.5 ° ± 1 °, 64 °. It shows a diffraction peak at ± 1 °. This is because a hexagonal oxide having a layered structure can be obtained when the X-ray diffraction pattern shows such a diffraction peak. The 38 ° ± 1 ° peak in this X-ray diffraction pattern is a peak obtained by overlapping the 36.5 ± 1 ° and 37.5 ± 1 ° peaks.

  Furthermore, the oxide used for the positive electrode active material of the present invention can be obtained by heating a plurality of compounds containing Li, Ni, Fe, M, O, and H at a temperature of 100 ° C. or higher and 250 ° C. or lower.

  A plurality of compounds containing Li, Ni, Fe, M, O, and H, which are starting materials, may or may not contain hydration water and crystallization water, but the oxide used for the positive electrode active material is water. It is preferable not to contain Japanese water. In addition, the oxide has oxygen-hydrogen bonds and may contain crystallization water, but the lower the crystallization water content, the better the cycle performance when the oxide is used as the positive electrode active material. Because.

  In order to remove hydrated water or crystal water from the obtained oxide, heat treatment may be performed at a temperature of 100 ° C. or higher. Furthermore, in order to remove hydration water in the positive electrode active material and promote crystallization of the positive electrode active material, a heat treatment at an intermediate temperature is effective.

  Moreover, although the oxide which is a positive electrode active material of the present invention has an oxygen-hydrogen bond, when the heat treatment temperature is too high, the oxygen-hydrogen bond may be broken. Therefore, the preferable heat treatment temperature is 100 ° C. or more and 250 ° C. or less, and the heat treatment temperature is most preferably in the range of 150 to 200 ° C.

  The atmosphere for the heat treatment of the oxide is not particularly limited, but an argon atmosphere is preferable in order to prevent a change in the composition of the oxide during the heat treatment.

  Further, although not shown in the examples, lithium can be introduced into the active material of the present invention by heat-treating the active material of the present invention with a lithium salt within a temperature range of 100 ° C. to 250 ° C. .

  The manufacturing method of the oxide used for the positive electrode active material of the present invention starts with a hydroxide whose transition metal has an average oxidation number of less than 3, and transition metal in an alkaline aqueous solution containing lithium ions or in an alcohol electrolyte. The effect of the invention can be further extracted when the oxidation is performed until the average oxidation number of becomes 3 or more.

  In the oxide of the present invention, a coprecipitation method is preferable as a method for mixing the transition metal at the atomic level. The starting transition metal hydroxide is dispersed in an aqueous solution of lithium hydroxide (LiOH) and oxidized with an oxidizing agent at a temperature of 80 ° C.

  The kind of oxidizing agent is not particularly limited. It is preferable to use at least one selected from oxygen, ozone or peroxodisulfate, or hypochlorite, permanganate, dichromate, bromine, and chlorine. Further, not only a chemical oxidation method using an oxidizing agent but also an electrochemical method may be used.

  As the negative electrode material used in the nonaqueous electrolyte battery of the present invention, a material capable of occluding and releasing metallic lithium and lithium ions is used. Examples of the substance capable of inserting and extracting lithium ions include graphite, amorphous carbon, oxide, nitride, and lithium alloy. As the lithium alloy, for example, an alloy of lithium and aluminum, zinc, bismuth, cadmium, antimony, silicon, lead, and tin can be used. Moreover, metals that are difficult to alloy with lithium, such as copper, nickel, titanium, and molybdenum, may be included as matrix metals of these alloy materials.

  Furthermore, according to the lithium content in the oxide which is the positive electrode active material of the present invention, a material containing lithium or a material not containing lithium can be used as the negative electrode active material. However, when the lithium content in the oxide which is the positive electrode active material of the present invention is small, that is, when the value of X / (Y + Z) is considerably smaller than 1, the negative electrode active material previously contains lithium. Is preferable, and a combination with lithium metal is particularly preferable.

  The non-aqueous electrolyte used in the non-aqueous electrolyte battery of the present invention may be a non-aqueous electrolyte, a polymer electrolyte, or a solid electrolyte. Solvents used for the non-aqueous electrolyte include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, γ-butyrolactone, sulfolane, dimethyl sulfoxide, acetonitrile, dimethylformamide, dimethylacetamide, 1,2-dimethoxyethane. And polar solvents such as 1,2-diethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, dioxolane and methyl acetate, and mixed solvents thereof.

Moreover, as a solute of the nonaqueous electrolytic solution, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiClO ₄ , LiSCN, LiCF ₃ CO ₂ , LiCF ₃ SO ₃ , LiN (SO ₂ CF ₃ ) ₂ , LiN (SO ₂ CF _2). Illustrative are salts such as CF ₃ ) ₂ , LiN (COCF ₃ ) ₂ and LiN (COCF ₂ CF ₃ ) ₂ or mixtures thereof.

  Below, the synthesis | combining method of the oxide used for the positive electrode active material of this invention and the nonaqueous electrolyte secondary battery using this oxide are demonstrated in detail based on an Example. However, the present invention is not limited to the following examples.

[Examples 1 to 4 and Comparative Examples 1 to 4]
[Example 1]
First, a 4M lithium hydroxide (LiOH) aqueous solution from which dissolved oxygen was removed with nitrogen was placed in a reaction vessel purged with nitrogen. Next, in this LiOH aqueous solution, nickel hydroxide (Ni (OH) ₂ ) and iron hydroxide (Fe (OH) ₂ ) are mixed so that the molar ratio of Ni: Fe is 97.5: 2.5. Dispersed.

Further, a LiOH aqueous solution in which Ni (OH) ₂ and Fe (OH) ₂ are dispersed is heated to 80 ° C., and 1.6 equivalents of NaClO are added to the total equivalent of Ni and Fe in this aqueous solution. Then, the mixture was stirred for 6 hours while maintaining 80 ° C. to be oxidized. Subsequent suction filtration and the resulting material was further dried at 65 ° C.

As a result of ICP analysis, the composition of the obtained final product oxide was Li _0.723 H _0.277 Ni _0.975 Fe _0.025 O ₂ .

  A positive electrode plate using the oxide thus obtained as a positive electrode active material was manufactured. An oxide 86 wt%, acetylene black 5 wt% as a conductive material, and polyvinylidene difluoride 9 wt% as a binder are mixed in a dry room using n-methyl-2-pyrrolidone (NMP) to form a paste Then, after applying to the aluminum net of the current collector, vacuum drying was performed at 70 ° C. to obtain a positive electrode plate having a mixture layer thickness of 180 μm and a size of 15 mm × 15 mm.

Using one positive electrode plate and two lithium metal plates of the same size as the negative electrode, the electrolyte contains 1 M lithium perchlorate (LiClO ₄ ) and ethylene carbonate (EC) and diethyl carbonate (DEC). A battery A1 according to the present invention was manufactured using 50 ml of the mixed solution.

[Example 2]
The composition is Li _0.827 H in the same manner as in Example 1 except that Ni (OH) ₂ and Fe (OH) ₂ dispersed in an LiOH aqueous solution have a Ni: Fe molar ratio of 95: 5. _An oxide of _0.173 Ni _0.95 Fe _0.05 O ₂ was obtained, and a battery A2 according to the present invention was produced using this as a positive electrode active material.

[Example 3]
The composition of Li (OH) ₂ and Fe (OH) ₂ dispersed in an LiOH aqueous solution was the same as that of Example 1 except that the molar ratio of Ni: Fe was 92.5: 7.5. _{An oxide of 0.643} H _0.357 Ni _0.925 Fe _0.075 O ₂ was obtained, and a battery A3 according to the present invention was produced using this as a positive electrode active material.

[Example 4]
The composition is Li _0.599 H in the same manner as in Example 1 except that Ni (OH) ₂ and Fe (OH) ₂ dispersed in an LiOH aqueous solution have a Ni: Fe molar ratio of 90:10. A battery A4 according to the present invention was prepared using _0.401 Ni _0.90 Fe _0.10 O ₂ as the positive electrode active material.

[Comparative Example 1]
An oxide having a composition of Li _0.619 H _0.381 NiO ₂ was obtained in the same manner as in Example 1 except that only Ni (OH) ₂ was dispersed in a LiOH aqueous solution, and this was obtained as a positive electrode active material. A battery B1 of Comparative Example 1 was prepared.

[Comparative Example 2]
The composition is Li _0.702 H in the same manner as in Example 1 except that Ni (OH) ₂ and Fe (OH) ₂ dispersed in an LiOH aqueous solution have a Ni: Fe molar ratio of 99: 1. _An oxide of _0.298 Ni _0.99 Fe _0.01 O ₂ was obtained, and a battery B2 of Comparative Example 2 was produced using this as a positive electrode active material.

[Comparative Example 3]
Ni dispersed in aqueous LiOH _{(OH) 2} and Fe _{(OH) 2} and Ni: except that the molar ratio of Fe was 85:15 in the same manner as in Example 1, the composition is _{Li 0.282} H _An oxide of _0.718 Ni _0.85 Fe _0.15 O ₂ was obtained, and a battery B3 of Comparative Example 3 was produced using this as a positive electrode active material.

[Comparative Example 4]
Ni (OH) ₂ was dispersed in distilled water at 50 ° C., 1.2 equivalents of NaClO were added, and the mixture was stirred for 6 hours while maintaining 50 ° C. to be oxidized. Subsequently, the solution was suction filtered and washed with distilled water. Moreover, after repeating this filtration water washing once, it dried at 65 degreeC. Thus, a battery B4 of Comparative Example 4 was produced in the same manner as in Example 1 except that HNiO ₂ having a composition was obtained and this was used as a positive electrode active material.

  Table 1 summarizes the contents of the positive electrode active materials used in the batteries of Examples 1 to 4 and Comparative Examples 1 to 4. In Table 1, the average valences of Ni and Fe were determined by oxidation-reduction titration using potassium permanganate.

[Charge / discharge test]
The batteries A1 to A4 of Examples 1 to 4 obtained by the above method and the batteries B1 to B4 of Comparative Examples 1 to 4 were constant current up to 4.2 V at 25 ° C. and a current density of 0.25 mA / cm ^2. After charging, discharging was performed at a constant current up to 1.5 V at a current density of 0.25 mA / cm ² . 20 cycles of charging and discharging were repeated under the same conditions.

  In Table 2, the result of the charging / discharging test of the battery of Examples 1-4 and Comparative Examples 1-4 was put together. Here, “capacity retention” was defined as the ratio (%) of the discharge capacity at the 20th cycle to the discharge capacity at the 1st cycle. In addition, the value of Table 1 shows the average value about each battery 10 cell.

  From the results in Tables 1 and 2, the following became clear. The batteries A1 to A4 of Examples 1 to 4 of the present invention using the positive electrode active material containing Fe have the same molar ratio as the battery B1 of Comparative Example 1 using the positive electrode active material B1 not containing Fe or Fe / (Fe + Ni). It was found that the charge / discharge cycle performance (capacity retention) was improved as compared with the battery B2 of Comparative Example 2 which was 0.01. In particular, in the batteries A2, A3, and A4 of Examples 2 to 4 having a Fe / (Ni + Fe) molar ratio of 0.05 to 0.10, the overall performance of the discharge capacity and the charge / discharge cycle performance is Comparative Example 1, 2 batteries B1 and B2. However, the battery B3 of Comparative Example 3 having a Fe / (Fe + Ni) molar ratio of 0.15 and the battery B4 of Comparative Example 4 using a positive electrode active material not containing lithium are not good in both discharge capacity and charge / discharge cycle performance. It was.

  The charge / discharge curve of the battery B1 of Comparative Example 1 is shown in FIG. 1, and the charge / discharge curve of the battery A3 of Example 3 is shown in FIG. 1 and 2, the symbol ■ indicates the charge curve of the first cycle, the symbol □ indicates the discharge curve of the first cycle, the symbol ● indicates the charge curve of the second cycle, and the symbol ○ indicates the discharge curve of the second cycle.

  As can be seen from FIG. 1, the discharge curve of the battery B1 of Comparative Example 1 was at least two stages. In contrast, the discharge curve of the battery A3 of Example 3 shown in FIG. 2 shows that the potential change is continuous and is more suitable for the secondary battery. Therefore, further improvement in performance was attempted for the positive electrode active material of Example A13 battery having good discharge performance.

[X-ray diffraction (XRD) measurement]
Powder XRD measurement was performed on the oxides used in Examples 1 to 3 and Comparative Example 3 using CuKα rays. The X-ray diffraction pattern is shown in FIG. In FIG. 3, symbol A is Li _0.723 H _0.277 Ni _0.975 Fe _0.025 O ₂ used in Example 1, and symbol B is Li _0.827 H _0.173 used in Example 2. Ni _0.95 Fe _0.05 O ₂ , symbol C is Li _0.643 H _0.357 Ni _0.925 Fe _0.075 O ₂ used in Example 3, symbol D is used in Comparative Example 3 of _{li 0.282 H 0.718 Ni 0.85 Fe 0.15} O 2, shows a X-ray diffraction pattern.

  In the oxides indicated by symbols A, B, and C in FIG. 3, diffraction angles (2θ) of 18.6 ° ± 1 °, 38 ° ± 1 °, 43.5 ° ± 1 °, 64 ° ± 1 ° Was found to show a diffraction peak. Note that the peak at 38 ° ± 1 ° in FIG. 3 is a peak obtained by overlapping the peaks at 36.5 ± 1 ° and 37.5 ± 1 °. From these results, it was found that in these oxides, a part of the Ni sites of the layered nickel oxyhydroxide in which Fe was replaced with lithium was replaced with Fe.

  As indicated by the symbol D in FIG. 3, the X-ray diffraction pattern of the oxide used in Comparative Example 3 has diffraction angles (2θ) of 18.6 ° ± 1 ° and 36.5 ± 1 °. Although a diffraction peak was shown, no diffraction peak was shown at 43.5 ° ± 1 ° and 64 ° ± 1 °, and a new peak was observed around 37.5 ± 1 °. It was found that the crystal structure of this oxide was a γ-type structure deviated from the hexagonal oxide.

  However, although no diffraction peak is shown, a new diffraction peak was observed in the vicinity of 12 ° on the low angle side in the positive electrode active material used in Comparative Example 4. This peak is clearly due to unreacted iron hydroxide or iron oxyhydroxide. From this, it can be said that there is a limit to the replacement of nickel oxyhydroxide with Ni sites by Fe.

  In addition, in the lithium-substituted nickel oxyhydroxide of Examples 1 to 4 in which the Ni site of nickel oxyhydroxide was substituted with 10 mol% or less of Fe, no clear diffraction peak was observed near 12 ° on the low angle side. . This indicates that the oxide used as the positive electrode active material in Examples 1 to 4 does not contain unreacted iron hydroxide or iron oxyhydroxide.

[Examples 6 to 11]
[Example 6]
An oxide having a composition of Li _0.643 H _0.357 Ni _0.925 Fe _0.075 O ₂ obtained in Example 3 was _converted to argon using an electric annular furnace (AT-E58 type) manufactured by Isuzu. Was heated for 16 hours at 100 ° C. A battery A6 of the present invention was produced in the same manner as in Example 1 except that this was used as the positive electrode active material.

[Example 7]
A battery A7 of the present invention was produced in the same manner as in Example 6 except that the heat treatment temperature was 150 ° C.

[Example 8]
A battery A8 of the present invention was produced in the same manner as in Example 6 except that the heat treatment temperature was 250 ° C.

[Example 9]
A battery A9 of the present invention was produced in the same manner as in Example 6 except that the heat treatment temperature was 400 ° C.

[Example 10]
A battery A10 of the present invention was produced in the same manner as in Example 6 except that the heat treatment temperature was 600 ° C.

[Example 11]
A battery A11 of the present invention was produced in the same manner as in Example 6 except that the heat treatment temperature was 800 ° C.

[Charge / discharge test]
The batteries A6 to A11 obtained in Examples 6 to 11 were charged at a constant current of up to 4.2 V at a current density of 0.25 mA / cm ² at 25 ° C., and then 1 at a current density of 0.25 mA / cm ^2. Discharge was performed at a constant current up to 5V. 20 cycles of charging and discharging were repeated under the same conditions.

  In Table 3, the heat processing temperature of the positive electrode active material used for battery A6-A11 of Examples 6-11 and the result of the charging / discharging test were put together. Here, “capacity retention” was defined as the ratio (%) of the discharge capacity at the 20th cycle to the discharge capacity at the 1st cycle. In addition, the value of Table 3 shows the average value about each battery 10 cell. Table 3 also shows data of Example 3 for comparison.

  As is clear from Table 3, in the batteries of Examples 6 to 11 in which the positive electrode active material used in Example 3 was heat-treated at 150 to 800 ° C., the discharge capacity was slightly reduced, but the charge / discharge cycle performance was remarkable. It turns out that it improves. It turned out that Examples 6-8 using especially the positive electrode active material heat-processed at the temperature of 100 to 250 degreeC show a big discharge capacity and favorable charging / discharging cycling performance.

  Since the positive electrode active material used in Example 7 and Example 8 was heat-treated at 250 ° C. or lower, the hydration water in the active material was removed, and the oxide in which oxygen-hydrogen bonds in the crystal existed stably Thus, it has been clarified that the discharge capacity and charge / discharge cycle performance of the positive electrode active material of the present invention are improved by securing the sites and diffusion paths where lithium can be inserted / released.

  On the other hand, for the positive electrode active materials used in Examples 9 to 11 heat-treated at a temperature of 400 ° C. or higher, the reason is not yet known, but Ni or Fe diffuses into the Li site, and Ni or Fe in the Li site. It is considered that the rock salt phase with the presence of is generated and the discharge capacity is reduced.

[Examples 12 to 15]
[Example 12]
In a LiOH aqueous solution, nickel hydroxide (Ni (OH) ₂ ), iron hydroxide (Fe (OH) ₂ ), and aluminum hydroxide (Al (OH) ₃ ) are mixed at a molar ratio of Ni: Fe: Al of 92. .5: 6.5: 1.0 The composition is Li _0.643 H _0.357 Ni _0.925 Fe _0.065 Al _0.010 O in the same manner as in Example 1 except that the dispersion is made to be 1.0. ₂ was obtained. This oxide was heat-treated at 350 ° C. for 16 hours while flowing argon using an electric annular furnace (AT-E58 type) manufactured by Isuzu. Then, in the same manner as in Example 1, a battery A12 according to the present invention was produced using this as a positive electrode active material.

[Example 13]
In a LiOH aqueous solution, nickel hydroxide (Ni (OH) ₂ ), iron hydroxide (Fe (OH) ₂ ), and aluminum hydroxide (Al (OH) ₃ ) are mixed at a molar ratio of Ni: Fe: Al of 92. .5: 2.5: 5.0 The composition is Li _0.643 H _0.357 Ni _0.925 Fe _0.025 Al _0.050 O in the same manner as in Example 1 except that the dispersion is made to be 2.5: 5.0. ₂ was obtained. This oxide was heat-treated under the same conditions as in Example 12 to make a battery A13 according to the present invention using this as a positive electrode active material, in the same manner as in Example 1.

[Example 14]
In a LiOH aqueous solution, nickel hydroxide (Ni (OH) ₂ ), iron hydroxide (Fe (OH) ₂ ), and zinc sulfate (ZnSO ₄ ) have a molar ratio of Ni: Fe: Zn of 92.5: 6. 5: _Oxide having a composition of Li _0.643 H _0.357 Ni _0.925 Fe _0.065 Zn _0.010 O ₂ in the same manner as in Example 1 except that the dispersion was made to be 1.0. Got. This oxide was heat-treated under the same conditions as in Example 12 to make a battery A14 according to the present invention using this as a positive electrode active material, in the same manner as in Example 1.

[Example 15]
In a LiOH aqueous solution, nickel hydroxide (Ni (OH) ₂ ), iron hydroxide (Fe (OH) ₂ ) and zinc hydroxide (ZnSO ₄ ) are mixed at a molar ratio of Ni: Fe: Zn of 92.5: 2. .5: _Oxidation having a composition of Li _0.643 H _0.357 Ni _0.925 Fe _0.025 Zn _0.050 O ₂ in the same manner as in Example 1 except that the dispersion was made to be 5.0. I got a thing. This oxide was heat-treated under the same conditions as in Example 12 to make a battery A15 according to the present invention using this as a positive electrode active material in the same manner as in Example 1.

[Charge / discharge test]
The batteries A12 to A15 obtained in Examples 12 to 15 were charged at a constant current of up to 4.2 V at a current density of 0.25 mA / cm ² at 25 ° C., and then 1 at a current density of 0.25 mA / cm ^2. Discharge was performed at a constant current up to 5V. 20 cycles of charging and discharging were repeated under the same conditions.

  Table 4 summarizes the compositions of the positive electrode active materials used in the batteries A12 to A15 of Examples 12 to 15 and the results of the charge / discharge test. Here, “capacity retention” was defined as the ratio (%) of the discharge capacity at the 20th cycle to the discharge capacity at the 1st cycle. In addition, the value of Table 4 shows the average value about each battery 10 cell. Table 4 also includes data of Example 7 for comparison.

  From Table 4, the batteries A12 and A13 of Examples 12 and 13 of the present invention using the positive electrode active material containing Fe and Al, and the Examples 14 and 15 of the present invention using the positive electrode active material containing Fe and Zn are shown. In the batteries A14 and A15, the discharge capacity was almost the same as the battery A7 of Example 7 containing only Fe, and the charge / discharge cycle performance (capacity retention) was superior to the battery A7 of Example 7.

This result is represented by the general formula _{Li x H 1-x Ni y} Fe z M a O 2 of the present invention, Li, H and Ni and Fe and M (where M = Al, Zn, Ca, Sr, Nb, By using an oxide containing at least one selected from the group consisting of Mg, Cd, Cu, V, Cr, Mo, Ti, W, and Ag as the positive electrode active material, the charge / discharge capacity and the charge / discharge potential It was found that a nonaqueous electrolyte battery excellent in characteristics and charge / discharge cycle performance was obtained.

The figure which shows the charging / discharging curve of battery B1 of the comparative example 1. FIG. The figure which shows the charging / discharging curve of battery A3 of Example 3. FIG. The X-ray-diffraction pattern of the oxide used in Example 1- Example 3 and Comparative Example 3 is shown.

Claims (3)

In the nonaqueous electrolyte battery comprising the positive electrode and the negative electrode, the general formula _{Li x H 1-x Ni y} Fe z M a O 2 ( where, M is Al, Zn, Ca, Sr, Nb, Mg, Cd, Cu, At least one selected from the group consisting of V, Cr, Mo, Ti, W, Ag, 0 <X / (Y + Z) ≦ 1, 0.95 ≦ Y + Z + a ≦ 1.1, 0.025 ≦ Z / (Y + Z) <0.1, 0 <= a <= 0.05) The nonaqueous electrolyte battery characterized by using the oxide represented by the positive electrode active material. In the X-ray diffraction pattern using CuKα ray of the oxide, diffraction peaks at diffraction angles (2θ) of 18.6 ° ± 1 °, 38 ° ± 1 °, 43.5 ° ± 1 °, 64 ° ± 1 ° The nonaqueous electrolyte battery according to claim 1, wherein The positive electrode active material for a non-aqueous electrolyte battery according to claim 1 or 2, wherein a plurality of compounds containing Li, Ni, Fe, M, O, and H are heated at a temperature of 100 ° C to 250 ° C. Manufacturing method.

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