JP2601777B2 - Electrodes for organic electrolyte batteries - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an electrode for an organic electrolyte battery, and more particularly, to an electrode for an organic electrolyte battery formed by molding an insoluble and infusible base powder containing a polyacene skeleton structure. About.

[Conventional technology]

2. Description of the Related Art In recent years, electronic devices have been remarkably reduced in size, thickness, and weight, and accordingly, there has been a great demand for smaller, thinner, and lighter batteries serving as power supplies. At present, silver oxide batteries are frequently used as small and high-performance batteries, and lithium batteries have been developed and commercialized as thin dry batteries and small and lightweight high-performance batteries. However, since these batteries are primary batteries, they cannot be repeatedly used and used for a long time. On the other hand, nickel-cadmium batteries have been put to practical use as high-performance secondary batteries, but they are still unsatisfactory in terms of miniaturization, thinning, and weight reduction.

In addition, lead storage batteries have conventionally been used in various industrial fields as large capacity secondary batteries, but the biggest disadvantage of these batteries is that they are heavy. This is fatal because lead peroxide and lead are used as electrodes. In recent years, attempts have been made to reduce the weight and improve the performance of batteries for electric vehicles, but they have not been put to practical use. There is still a strong demand for a large-capacity and lightweight secondary battery as an energy source.

As described above, batteries that are currently in practical use have advantages and disadvantages and are used properly according to their applications. However, there is a great need for batteries that are smaller, thinner, or lighter. In recent years, as a battery that meets such needs, a battery using, as an electrode active material, a thin-film polyacetylene that is an organic semiconductor doped with an electron donor or an electron acceptor has been studied and proposed. Although this battery has high performance as a secondary battery and has the potential of being thinner and lighter, it has major drawbacks. It is a substance in which polyacetylene, an organic semiconductor, is extremely unstable, and is easily oxidized by oxygen in the air and may be deteriorated by heat. Therefore, the battery must be manufactured in an inert gas atmosphere, and there is a limitation in manufacturing polyacetylene into a shape suitable for an electrode.

On the other hand, JP-A-60-170163 by the applicant of the present application discloses a heat-treated product of an aromatic condensation polymer composed of carbon, hydrogen and oxygen, wherein the atomic ratio of hydrogen atoms / carbon atoms is 0.05 to 0.05. 0.5 and the specific surface area by BET method is
An insoluble and infusible substrate having a polyacene-based skeleton structure of at least 600 m ² / g is used as a positive electrode and / or a negative electrode, and an aprotic organic solvent solution of a compound capable of generating ions that can be doped into the electrode by electrolysis is used as an electrolyte. An organic electrolyte battery characterized by the following has been proposed.

The insoluble and infusible substrate having a polyacene-based skeleton structure used as an electrode in the battery is stable in air and practical as an industrial material, and thus is suitable as an electrode for an organic electrolyte battery.

Further, Japanese Patent Application Laid-Open No. 62-133283 by the applicant of the present application discloses a heat-treated phenolic resin having a polyacene skeleton structure having a hydrogen atom / carbon atom ratio of 0.5 to 0.05, and a BET At least 600m ² / g
In the method for producing a battery electrode comprising an insoluble infusible substrate, the powder of the insoluble infusible substrate is mixed with a conductive material and a binder, and the mixture is molded under pressure or applied or pressed on a support. A method for producing a battery electrode characterized in that the electrode is attached is proposed.

The method for producing the electrode is simple, has excellent moldability, is extremely practical, and has high productivity. However, it was still unsatisfactory in terms of the capacity per unit volume, which is one of the most important performances of the battery.

 Generally, the capacity per unit volume is expressed by the following equation.

Capacity per unit volume = capacity per unit weight × electrode density That is, when the capacity per unit weight is constant, it can be said that the higher the electrode density, the more advantageous. However, in the above-described conventional method, when the electrode density is to be increased, the capacity per unit weight is drastically reduced, and the capacity per unit volume cannot be greatly increased.

[Problems to be solved by the invention]

The present inventors have completed the present invention as a result of intensive studies in view of the above-mentioned problems of the existing electrode for an organic electrolyte battery, and the purpose thereof is to achieve a high capacity per unit volume. To provide an electrode for an organic electrolyte battery having the same. Another object of the present invention is to provide an electrode for an organic electrolyte battery which is easy to manufacture and can be processed into an arbitrary shape.

[Means for solving the problem]

The above objects are (1) a heat-treated aromatic resin containing at least 10% by weight or more of a thermosetting resin component containing nitrogen, and (a) a hydrogen atom / carbon atom number ratio of 0.05 to 0.5. And a polyacene skeleton structure having an atomic ratio of nitrogen atoms / carbon atoms of at least 0.01; (b) a specific surface area value of at least 600 m ² / g by a BET method; and (c) a tap density of 0.35 g. / cm ³ or more, which is achieved by an electrode for an organic electrolyte battery comprising a molded product of an insoluble and infusible substrate powder.

In the present invention, the aromatic resin containing a thermosetting resin component containing nitrogen is a blend resin of a thermosetting resin containing nitrogen and an aromatic resin, and also contains a predetermined amount of nitrogen. It may be a condensate of a thermosetting resin component and an aromatic resin component, or may be an aromatic resin composed of a thermosetting resin component further containing nitrogen. Preferred examples of the thermosetting resin component containing nitrogen include those which condense with aldehydes under acidic or basic conditions, such as melamine, urea, and aniline. In addition, a phenolic resin is generally used as the aromatic resin component in the present invention.

Here, the phenolic resin is a condensate of an aromatic hydrocarbon compound having a phenolic hydroxyl group with an aldehyde. As the aromatic hydrocarbon compound, for example, so-called phenols such as phenol, cresol and xylenol are suitable, but not limited thereto. For example, Methylene bisphenols, or hydroxy-biphenyls and hydroxynaphthalenes. Of these, phenols, particularly phenol, are practically preferred.

As the phenolic resin in the present invention, a modified aromatic polymer obtained by substituting a part of the aromatic hydrocarbon compound having a phenolic hydroxyl group with an aromatic hydrocarbon compound having no phenolic hydroxyl group, for example, xylene, toluene, aniline, etc. For example, a condensate of phenol, xylene and formaldehyde can be used, and furthermore, a furan resin can be used. As the aldehyde, formaldehyde, acetaldehyde, furfural and the like can be used, but formaldehyde is preferred.

In the present invention, the content of the nitrogen-containing thermosetting resin component is required to be 10% by weight or more, preferably 40 to 70% by weight, based on the total amount of the aromatic resin. If the thermosetting resin component containing nitrogen is less than 10% by weight, increasing the density of the electrode will decrease the capacity per unit weight.

In the present invention, the aromatic resin containing at least 10% by weight or more of the nitrogen-containing thermosetting resin component is, for example, an initial mixture of a nitrogen-containing thermosetting resin such as a melamine resin, a phenolic resin such as a water-soluble resol, and an aldehyde. A method of mixing a condensate, a method of co-condensing a thermosetting resin component (monomer) containing nitrogen, a phenolic resin component (monomer) and aldehydes, or a method of further blending an aromatic resin therewith Can be manufactured.

The insoluble and infusible base powder having a polyacene-based skeleton structure used in the present invention can be produced, for example, as follows.

A slurry is prepared by mixing an initial condensate of a thermosetting resin component containing nitrogen and a phenolic resin component, and an aqueous solution of an inorganic salt such as zinc chloride, and the slurry is heated and cured. At this time, the thermosetting resin component containing nitrogen may be in the form of a powder, a solution, or the like, but is preferably a substantially spherical one.

As such a thermosetting resin component containing substantially spherical nitrogen, those having an average particle diameter of 200 μm or less are desirable, and commercially available products such as a melamine resin WAC type manufactured by Unitika Ltd. can be used. If the average particle size of the substantially spherical thermosetting resin component containing nitrogen exceeds 200 μm, the dispersibility becomes extremely poor. Therefore, the average particle size of the substantially spherical thermosetting resin containing nitrogen is preferably as small as possible.
It is preferably not more than μm. Further, the shape of the substantially spherical thermosetting resin component containing nitrogen may not be a true sphere, and may be, for example, an oval shape in which the true sphere is deformed. What is important is that the powder has a good flow so that the substantially spherical thermosetting resin component containing nitrogen can be sufficiently homogeneously dispersed when mixed with other components.

The zinc chloride used together with the initial condensate at the time of mixing is removed in a later step, imparts pores to the cured product, and acts as a pore forming agent for forming a high specific surface. It can be used in a weight-fold amount. If it is less than 2.5 times by weight, it is difficult to obtain a porous body having a high specific surface area, and if it exceeds 10 times by weight, the yield of the heat-treated product is reduced. The aqueous solution of the initial condensate and zinc chloride can be adjusted using, for example, 0.1 to 1.0 times the weight of zinc chloride.

The cured product thus obtained is then placed in a non-oxidizing atmosphere
It is heated to a temperature of 350 to 800 ° C, preferably to a temperature of 350 to 700 ° C, particularly preferably to a temperature of 400 to 600 ° C, and heat-treated.

The preferred sound heating rate during the heat treatment is slightly different depending on the degree of the curing treatment or the shape thereof, but it is generally possible to use a relatively large heating rate from room temperature to a temperature of about 300 ° C. A rate of ° C./hour is also possible.

Such heat treatment of the cured resin is performed in a non-oxidizing atmosphere. The non-oxidizing atmosphere is, for example, nitrogen,
It is an atmosphere of argon, helium, neon, carbon dioxide or vacuum, and nitrogen is preferably used. Such a non-oxidizing atmosphere may be stationary or flowing.

By sufficiently washing the obtained heat-treated body with water or dilute hydrochloric acid, etc., zinc chloride contained in the heat-treated body can be removed, and then dried to obtain a porous cured condensate having a large specific surface area. Can be.

Thus, by the heat treatment, the atomic ratio of hydrogen atoms / carbon atoms (hereinafter referred to as H / C ratio) is 0.5 to 0.05, preferably 0.35 to 0.1, and the atomic ratio of nitrogen atoms / carbon atoms is 0.01 to 0.01.
As described above, an insoluble and infusible substrate having a polyacene skeleton structure of preferably 0.5 to 0.01 is obtained.

It is understood that the insoluble infusible substrate has a structure in which a part of carbons of a polyacene-based polycyclic structure is replaced with nitrogen, which is uniformly and appropriately developed between polyacene-based molecules.

The electrode for an organic electrolyte battery in the present invention is obtained by molding a powder of an insoluble and infusible substrate containing a polyacene-based skeleton structure obtained by the above-described method. The insoluble and infusible substrate powder needs to have a tap density of 0.35 g / cm ³ or more.

Here, the “tap density” means a bulk density when the powder is repeatedly subjected to a light impact and filled into a container, and is an index indicating the particle size of the powder, packing property, and the like. When the tap density is less than 0.35 g / cm ^3, it is difficult to increase the density of the electrode obtained by molding the powder, and thus it is difficult to obtain an electrode having a large capacity per unit volume. When using an insoluble and infusible base powder composed of a heat-treated aromatic resin containing less than 10% by weight of a thermosetting resin component containing nitrogen, when the tap density becomes 0.35 g / cm ³ or more, In addition, the density of the compact can be increased. However, at the same time, the capacity per unit weight is greatly reduced, so that an electrode having a large capacity per unit volume cannot be obtained.

However, at least a thermosetting resin component containing nitrogen is used.
Only when using an insoluble and infusible substrate powder consisting of a heat-treated aromatic resin containing 10% by weight or more, the tap density is reduced.
Even if 0.35 g / cm ³ or more, the capacity per unit weight does not decrease, that is, the capacity per unit volume can be increased.

In order to produce a relatively high pulverization powder having a tap density of 0.35 g / cm ³ or more in a shorter time, it is preferable to use a relatively powerful pulverization method such as an alumina ball mill. In this case, the pulverization time is preferably set within 10 to 200 hours, but should be appropriately determined depending on the amount of pulverization and physical properties of the desired powder.

However, the specific surface area of the ground powder by the BET method is 600.
It is preferably at least m ² / g. Specific surface area value is 600m ² / g
If it is less than 7, it is necessary to increase the charging voltage when charging the secondary battery using the electrode of the present invention, so that the energy density and the like are reduced, and the electrolyte is deteriorated.

By shaping the insoluble and infusible substrate powder thus obtained, the electrode for an organic electrolyte battery aimed at by the present invention can be obtained. The molding of the powder may be carried out by selecting a known appropriate method, for example, a method of adding a current collector to the insoluble and infusible base powder and binding with an organic binder. As a current collector to be used, carbon black, acetylene black and the like are preferable, and a Teflon-based organic binder is preferable.

(Effect of the Invention) The electrode for an organic electrolyte battery of the present invention thus obtained is
Higher density than conventional products and high capacity per unit weight. That is, the electrode for an organic electrolyte battery has an excellent capacity per unit volume.

 Hereinafter, the present invention will be described specifically with reference to examples.

Example 1 A substantially spherical melamine resin having an average particle diameter of 60 μm and an aqueous solution of a resol-type phenolic resin (resin component: 75%) were mixed so as to have a weight ratio of 1: 1 in terms of resin solid content, and the solid content of the mixture was determined. A slurry obtained by mixing zinc chloride three times the weight and water five times the weight in a minute was poured into a mold and heated at about 100 ° C. for 2 hours to cure.

Put the cured product in a silicon knit electric furnace under a nitrogen stream
The temperature was raised at a rate of 40 ° C./hour and heat treatment was performed up to 550 ° C. Next, the heat-treated product was washed with dilute hydrochloric acid, washed with water, and dried to obtain an insoluble and infusible substrate. The specific surface area of this insoluble and infusible substrate determined by the BET method was 2120 m ² / g.

Then, the insoluble and infusible substrate was pulverized by an alumina ball mill, and two kinds of powders after pulverization Comparative Example A and Example B
And got. The tap density of each of these powders is 0.32 g /
cm ³ and and 0.38 g / cm ^3, also the BET specific surface area 1
650 m ² / g and 1030 m ² / g.

Next, 5 parts by weight of polytetrafluoroethylene as a binder was added to 100 parts by weight of each of these powders, kneaded in a mortar, and formed into a plate-like film with a roller to obtain two types of electrodes.

Two types of batteries were prepared using the thus obtained molded articles as a positive electrode, lithium metal as a negative electrode, and 1.0 mol of LiClO ₄ dissolved in 1 of sufficiently dehydrated propylene carbonate as an electrolyte. 0.5mA /
Charge and discharge were performed at ² V to 4 V at a current density of cm ^{2, and} the capacities were measured. The results are shown in Table 1.

As shown in Table 1, when comparing Comparative Example A and Example B in which melamine resin was mixed, Example B showed a large increase in the electrode density with an increase in tap density, but the capacity per weight was almost maintained. is the capacity of this order per volume is seen to increase significantly from 55mAh / cm ³ Comparative example a and 65.6mAh / cm ³ in example B.

Example 2 A slurry was prepared by mixing zinc chloride three times the weight of a resin component and water three times the weight of a resin component with respect to an aromatic polymer consisting only of a resole type phenol resin aqueous solution (resin component 75%). Hardening, baking and washing were performed in exactly the same manner as in Example 1 to obtain an insoluble and infusible substrate. The specific surface area of this insoluble and infusible substrate as measured by the BET method was 2200 m ² / g.

Next, the powder was pulverized at different times in the same manner as in Example 1 to obtain two types of powder Comparative Examples C and D having tap densities of 0.33 g / cm ³ and 0.38 g / cm ³ , respectively. The specific surface area values of these powders by the BET method were 1610 m ² / g and 109
It was 0 m ² / g.

Each of these powders was molded in the same manner as in Example 1 to form an electrode, and then a lithium battery was produced and its capacity was measured. The results are shown in Table 1 above.

As shown in Table 1, when Comparative Examples C and D in which relamine resin was not mixed and Comparative Examples A and Example B in which melamine resin was mixed, Comparative Example D showed an increase in tap density more than Comparative Example C. The electrode density has increased significantly. However, the capacity per weight was not maintained as in Example B, but rather, 75.1 mA of Comparative Example C.
h / g was drastically reduced to 54.0 mAh / g in Comparative Example D, and thus the capacity per unit volume was found to decrease rather than increase.

Example 3 Fragrance in which the weight ratio of a substantially spherical melamine resin having an average particle diameter of 60 μm to a resin component in a resol-type phenol resin aqueous solution (resin solid content: 75%) was changed in six ways as shown in Table 2. A slurry was prepared by mixing zinc chloride and water in the same weight ratio as in Example 1 with respect to the group-based resin. Example 1
Heat treatment, washing, and the like were performed in the same manner as described above to obtain an insoluble and infusible substrate.

Next, these were ground for about 90 to 100 minutes using a disk mill. Further, these powders were molded, lithium batteries were prepared in the same manner as in Example 1, and their capacities were measured. Table 2 shows the tap density, electrode density, and battery capacity.

Claims (1)

(57) [Claims] (1) a thermosetting resin component containing nitrogen,
A heat-treated aromatic resin containing 10% by weight or more of: (a) a polyacene-based resin having an atomic ratio of hydrogen atoms / carbon atoms of 0.05 to 0.5 and an atomic ratio of nitrogen atoms / carbon atoms of at least 0.01. (B) having a specific surface area value of at least 600 m ² / g by a BET method, and (c) having a tap density of not less than 0.35 g / cm ³ , comprising a molded body of an insoluble and infusible base powder. Electrodes for organic electrolyte batteries.