JP2940181B2 - Solid electrode composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrode composition used for electrochemical devices such as batteries, capacitors, sensors, display devices and recording devices.

[0002]

2. Description of the Related Art In a general electrochemical device, a solid electrolyte is used in place of a conventional liquid electrolyte without liquid leakage, and a solid electrolyte such as a small and thin battery or an electric double layer capacitor is used. An electrochemical device can be obtained.

[0003] However, since these electrochemical devices are composed of a solid material lacking in elasticity, they have a drawback that they are extremely brittle against mechanical shock and are easily broken. In order to solve such a problem, a solid polymer electrolyte composed of polyethylene oxide (PEO) and an alkali metal salt has been proposed ("Fast Ion Transpor").
t in Solid "P.Vanishstaet.al., Eds. P. 131 (1979) N
orth Holand Publishing Co.).

[0004] A polymer solid electrolyte is lighter, more flexible, and more excellent in moldability than an inorganic solid electrolyte. Since then, research and development of materials exhibiting high ionic conductivity comparable to inorganic solid electrolytes while maintaining excellent flexibility and moldability have been actively conducted. Then, these polymer electrolytes are mixed with an electrode material made of an inorganic compound such as vanadium pentoxide or an organic material such as polyaniline to form a solid electrode composition, and the electrode composition is formed through the polymer electrolyte. Batteries in solid state by joining are currently proposed.

[0005]

However, in the above-mentioned conventional electrode compositions, the electrode material and the polymer electrolyte are not always homogeneously dispersed and mixed.
Insufficient networks for ionic and electronic conduction, for example, Journal of Powder Sources, Vol. 28, 397-40
As described on page 8 (1987), a polymer solid electrolyte (SP) composed of polyethylene oxide dissolved in LiCF ₃ SO ₃
E), a lithium anode, and a cathode composed of a mixture of amorphous V ₂ O ₅ , SPE, and carbon black, have a utilization rate of about 10% (discharge current density: 0.33 mA /
cm ² , temperature: 20 ° C.), and there was a problem that the electrode material was not sufficiently used.

[0006] The present invention is to solve the above problems,
It is an object of the present invention to provide a solid electrode composition having good uniform formability and excellent ion conductivity and electron conductivity.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an electrode active material, a conductive material if necessary, and a polyamine obtained by adding ethylene oxide (EO) and butylene oxide (BO) to a polyamine compound. A compound, an ion-exchangeable layered compound, and an ionic substance represented by the formula MX (where M is a metal ion, proton, or ammonium ion that moves in the solid electrode composition under the action of an electric field, and X is a strong acid ), And ion-conductive particles for the purpose of increasing ionic conductivity in the electrode composition.

[0008]

Therefore, according to the present invention, the ionic substance MX forms a complex between the polyether compound and the ion-exchangeable layered compound and is maintained at a high concentration between the layers or surfaces of the crystal of the layered compound, which is advantageous for ion conduction. The active material powder and, if necessary, the conductive material powder are uniformly mixed with the solvent and ion-exchangeable layered compound by the action of the polyether compound surfactant, and are necessary for the battery reaction. Forms a conductive path for electrons and ions, and furthermore, during addition and mixing of the ion-conductive powder, the polyether compound prevents the aggregation of the ion-conductive powder, and forms a layered compound and an electron-conductive electrode that are ion-exchangeable with the solvent. In order to enable uniform mixing and dispersion with the active material and the conductive material, high electron and ion conductivity and homogeneity can be obtained. As a result, an electrode composition having low polarization and high electrode utilization is obtained. Further, the polyethylene oxide chain and butylene oxide chain of the polyether compound are entangled with the microporous structure of the ion-exchangeable layered compound, so that good moldability and sufficient mechanical strength are provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail. Further, in the following examples, parts,%, and ratio represent parts by weight,% by weight, and ratio by weight unless otherwise specified.

In the present invention, the electrode active material or the conductive material may be a single metal such as metallic copper, metallic silver or metallic lithium;
Alloys such as Li-Al and LaNi ₅ , copper sulfide, silver sulfide, copper sublel compounds, silver sublel compounds, titanium sulfide, niobium sulfide, metal sulfides such as molybdenum sulfide, manganese dioxide,
Use solid materials at room temperature, such as metal oxides such as vanadium oxide, cobalt oxide, and chromium oxide; halides such as silver chloride, lead iodide, and carbon fluoride; and carbon materials such as activated carbon, graphite, and carbon black. Can be. As the shape, any of ultrafine particles having an average particle diameter of 1 μm or less to particles of several tens μm can be used.

The polyether compound of the present invention obtained by adding ethylene oxide and butylene oxide to the polyamine compound is obtained by subjecting the polyamine compound to addition reaction of ethylene oxide and butylene oxide at 100-180 ° C. and 1-10 atm under an alkali catalyst. Obtainable. As the polyamine compound, polyethyleneimine, polyalkylenepolyamine or a derivative thereof can be used. Examples of the polyalkylene polyamine include diethylene triamine, triethylene tetramine, hexamethylene tetramine, dipropylene triamine and the like. The addition mole number of ethylene oxide and butylene oxide is 2 to 150 moles per active hydrogen of the polyamine compound. The ratio of ethylene oxide (EO) and butylene oxide (BO) to be added is 80/20 to 10/90 (= EO / BO). The polyether thus obtained has an average molecular weight of 100
0 to 5 million. The addition amount of the polyether compound is
It is preferably 0.5 to 20% based on the total amount of the solid electrode composition.

[0012] The ionic substance is not particularly limited.
But LiI, LiClO_Four, LiCF_ThreeSO_Three, LiPF₆, LiBF _Four, LiSCN, LiAsF₆, N
aI, NaSCN, NaBr, KI, AgNO_Three, CuCl_Two, Mg (ClO_Four)_Two, ZnCl_Two, AlCl_Three
Soluble salts are used.

Examples of the ion-exchangeable layered compound include clay minerals including silicates such as montmorillonite, hectorite, saponite, smectite, zirconium phosphate,
Examples thereof include phosphoric esters such as titanium phosphate, vanadic acid, antimonic acid, tungstic acid, and those modified with organic cations such as quaternary ammonium salts or organic polar compounds such as ethylene oxide and butylene oxide.

Further, in the solid electrode composition of the present invention,
It is also possible to add an ion-conductive powder of You
That is, MeCu is used as the ion conductive powder._FourI_2-xCl_{3 + x}(x
= 0.25-1.0, Me = Rb, K, NH_FourOr a mixture of them)
And CuI-Cu_TwoO-MoO_ThreeCopper ion conductive solid electrolysis of glass etc.
Quality, RbAg_FourI_Five, Ag_ThreeSi, AgI-Ag_TwoO-MoO_ThreeGlass, Ag₆I_FourWO_Four
Silver ion conductive solid electrolytes such as LiI, LiI.H_TwoO, Li-β
-Al_TwoO_Three, LiI-Li_TwoS-B_TwoS_Three, PEO-LiCF_ThreeSO_ThreeSuch as lithium ion
On-conductive solid electrolyte, H_ThreeMo₁₂PO₄₀・ 29H_TwoO, H_ThreeW ₁₂PO₄₀
・ 29H_TwoUse of proton conductive solid electrolytes such as O
it can. Its shape is ultrafine with an average particle size of 1 μm or less.
Use any particle size from several tens of μm
Can be. The amount of the above ion conductive powder is
There is no limitation as long as the moldability of the polar composition is not impaired.

The solid electrode composition of the present invention is obtained as follows. A powder of an ion-exchangeable layered compound is added to a solvent in which 1 to 50% of an ionic substance is dissolved so as to have a concentration of 1 to 50%. The mixture is pulverized and mixed by a mixing pulverizer such as a disperser to prepare an electrolyte slurry having a solid content of 5 to 95%.

Further, a powder of an electrode active material and, if necessary, a polyether compound solution containing 0.1 to 20% of a polyether compound having an EO chain and a BO chain in a solvent in which 1 to 50% of an ionic substance is dissolved. A powder obtained by previously mixing a powder of an electrode active material and a conductive material is added to form an electrode slurry. Next, the electrolyte slurry and the electrode slurry are mixed to obtain an electrode composition slurry. Mixing has a diameter of 3-10
It is preferably carried out in an alumina ball mill together with mm alumina spheres. The electrode composition slurry thus obtained is cast or molded on a support such as a fluororesin plate or a nylon mesh sheet, and then molded, and then the solid electrolyte composition is formed by dispersing a part or all of the solvent. Can be obtained. If the support is in a mesh form, it can be used as a solid electrode composition while the support is integrated.

If necessary, these steps may be performed at a relative humidity of 4
It is performed in a dry atmosphere of 0% or less. Further, as the solvent, acetone, methyl ethyl ketone, ketone solvents such as methyl isobutyl ketone, n-hexane, n-heptane,
saturated hydrocarbon solvents such as n-octane and cyclohexane,
Aromatic solvents such as benzene, toluene and xylene; ester solvents such as ethyl acetate, butyl acetate and propylene carbonate; alcohol solvents such as methanol, ethanol, isopropyl alcohol, ethylene glycol, glycerin and polyethylene glycol; nitriles such as acetonitrile Or water.

(Example 1) Polyethyleneimine containing 10 N atoms in a molecule was converted to ethylene oxide (E
O) and butylene oxide (BO) are added so that the ratio of EO to BO is 30/70, and the average molecular weight obtained is 1
An 80,000 polyether compound was dissolved in acetonitrile to prepare a 20% polyether solution.

Further, LiCF ₃ SO ₃ is used as an ionic substance.
30% solid content in 0% dissolved polyether solution
Γ-zirconium phosphate powder having an average particle size of 15 μm was added thereto and stirred and mixed at 40 ° C. for 24 hours to obtain an electrolyte slurry. Next, niobium sulfide powder (NbS ₂ ) having an average particle size of 6 μm was added to the polyether solution at a solid content of 50 μm.
%, And mixed at 40 ° C. for 24 hours to obtain an electrode slurry. The electrolyte slurry and the electrode slurry are mixed in an alumina ball mill at a solid content ratio of 1: 2.
After mixing for an hour, an electrode composition slurry was obtained. The electrode composition slurry was applied on a smooth fluororesin plate using a doctor blade, then dried in a dry argon gas stream at 130 ° C. for 1 hour, and further vacuum-dried for 5 hours to obtain a size of 80 × 80 mm and a thickness of 80 × 80 mm. A 140 μm sheet-shaped solid electrode composition was obtained. In addition, in order to construct a battery, only the electrolyte slurry is coated and dried in the same manner, and the size is 80 × 80.
An electrolyte sheet having a thickness of 55 mm and a thickness of 55 microns was prepared.

Example 2 The average particle diameter obtained by hydrolysis of vanadium butoxide as an electrode active material was 0.5 μm.
1 part of vanadium oxide powder having an average particle size of 0.02 μm
m and 0.1 parts of furnace black mixed with ethanol as a dispersion medium and dried was used as an electrode powder, and EO and BO were added to triethylenetetramine at EO / BO = 80.
/ 20 (weight ratio) obtained by dissolving a polyether compound having an average molecular weight of 8000 in acetonitrile, a 10% polyether solution, a montmorillonite powder having an average particle size of 5 μm, and an ionic substance. A sheet-like solid electrode composition having a thickness of 135 μm and a sheet-like electrolyte having a thickness of 60 μm were produced in the same manner as in Example 1 except that lithium trifluorosulfonate (LiCF ₃ SO ₃ ) was used.

Example 3 One part of a lithium-manganese composite oxide (LiMn ₂ O ₄ ) powder having an average particle diameter of 7 μm obtained by thermally decomposing a mixture of lithium carbonate and manganese carbonate, and an average particle diameter of 0.1 μm. A mixture of 0.2 parts of 02 micron furnace black was used as an electrode active material, and EO and BO were added to hexamethylenetetramine as EO / BO = 60 /
The average molecular weight obtained by adding at a ratio of 40 is 15
000 polyether compound dissolved in acetonitrile, a 10% polyether solution, and γ having an average particle size of 8 μm.
-Using zirconium phosphate powder, lithium perchlorate (LiClO ₄ ) as an ionic substance, and a lithium compound composed of Li ₃ N, LiI, and B ₂ O ₃ as an ion-conductive solid electrolyte. As in Example 1, the size was 80 × 80 mm, and the thickness was 155, except that 5% was mixed.
A sheet-shaped solid electrode composition having a thickness of μm and a sheet-shaped electrolyte having a thickness of 50 μm were prepared.

[0022]

[Comparative Example] LiCF ₃ SO ₃ was added in an amount of 8 per ethylene oxide molecule.
One-third of the polymer solid electrolyte made of polyethylene oxide having an average molecular weight of 4.8 million was mixed with the same electrode active material as in Example 2, and dried to a thickness of 135 μm.
An m-sheet solid electrode composition was prepared. In addition, thickness 6
A sheet electrolyte of 0 μm was produced.

Evaluation of Characteristics of Solid Electrode Composition Using the solid electrode compositions obtained in Examples 1 to 3 and Comparative Example, a disk having a diameter of 10 mm was punched out to obtain a sample for a characteristic test. In addition, the sheet electrolyte prepared in each of the examples was punched into a 10 mm diameter and used for a battery configuration. After disposing a metal lithium disc having a thickness of 2 mm and a diameter of 10 mm on one surface of the electrolyte disc, disposing a disc of the solid electrode composition on the other face, and further disposing platinum discs above and below the whole, Is pressurized from above and below at a pressure of 50 kg / cm ² , and 80 wt.
C. for 3 hours to assemble 10 test batteries A (Example 1), 10 test batteries B (Example 2), 10 test batteries C (Example 3), and 10 test batteries B '(Comparative Example). After charging the test battery at a constant voltage of 3.5 V for 17 hours, 0.05
Discharge was performed at a constant current of mA for 10 seconds, and a difference (polarization) between the battery voltages immediately before and immediately after the discharge was measured, and an average value and a standard deviation value were obtained for 10 batteries. In addition, a continuous discharge was performed to 0.3 volt at the same current value to obtain a discharge capacity,
The utilization rate of the electrode active material with respect to the theoretical capacity (100%) was determined. The results of the polarization values are shown in (Table 1), and the utilization rates of the electrodes are shown in (Table 2). The electrode utilization was evaluated assuming that 1 mol of Li reacted with 1 mol of NbS ₂ , V ₂ O ₅ , and LiMn ₂ O ₄ as 100%.

[0024]

[Table 1]

[0025]

[Table 2]

As is clear from the above examples and the results shown in (Table 1) and (Table 2), the solid electrode composition according to this example has an electrode utilization rate of 30% or more and a standard deviation of polarization. The value is small, indicating that the electrode active material and the solid electrolyte are a homogeneous electrode composition that is uniformly mixed.

Further, the mechanical strength of the solid electrode composition of the present example was determined by repeatedly bending a molded body having a length of 40 mm and a width of 5 mm along a curved surface having a radius of 50 mm at a rate of twice per second. When evaluated by the number of times up to breakage, it was found that even after 800 times of the bending test, the original shape was maintained without breakage, and that it had excellent mechanical strength.

[0028]

As is apparent from the above examples, according to the present invention, a uniform polyelectrode active material and a conductive material are uniformly dispersed by the action of a specific polyether compound having an ethylene oxide chain and a butylene oxide chain. A solid electrode composition can be provided. The polyether compound forms a complex with the ion-exchangeable layered compound, and is maintained at a high concentration between layers or on the surface of the crystal of the layered compound to form a favorable path for ion conduction. The ion conduction path necessary for the smooth progression of the battery reaction can be formed, and the electron and ion conduction paths are formed uniformly, so that high electrode utilization, small polarization, and uniform characteristics can be obtained. it can.

Continuing on the front page (72) Inventor Teruhisa Kamihara 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Kenichi Takeyama 1006 Kadoma, Kazuma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-4-248258 (JP, A) JP-A-1-169875 (JP, A) JP-A-59-160963 (JP, A) JP-A-59-143268 (JP, A) JP-A-3-95802 (JP, A) JP-A-4-33261 (JP, A) JP-A-4-33262 ( JP, A) JP-A-4-33263 (JP, A) JP-A-63-245871 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 4/62 C08G 65/26 C09K 3/00 H01M 4/02 H01M 4/06

Claims (2)

(57) [Claims] 1. An electrode active material, a polyether compound obtained by adding ethylene oxide and butylene oxide to a polyamine compound, an ion-exchangeable layered compound,
An ionic substance represented by X (where M is the action of an electric field)
A metal ion, a proton, and an ammonium ion that move in the solid electrode composition , and X is an anion of a strong acid)
And a solid electrode composition comprising: 2. The solid electrode composition according to claim 1, wherein a conductive material is mixed.