JP2003142102A - Electrode and battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode capable of minimizing internal resistance when applied to a battery. SOLUTION: The electrode has a current collector and a compound layer formed on the current collector containing an active material and an adhesive material which is a water-soluble cellulose derivative comprising a long chain alkyl group. Specifically, the water-soluble cellulose derivative is preferably a compound containing at least one selected from hydroxyethyl group and hydroxypropyl group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode characterized by a binder and a battery to which the electrode is applied.

[0002]

2. Description of the Related Art In recent years, the development of cordless electronic devices such as video cameras and mobile phones has been remarkable, and non-aqueous electrolytes such as lithium secondary batteries having a high battery voltage and a high energy density have been used as power sources for these consumer applications. Secondary batteries are drawing attention and are being put to practical use.

As a positive electrode active material for lithium batteries, Li_X
CoO₂, Li_XNiO₂, Li_XMn ₂O_Four, Li_XFe
O₂, V₂O_Five, Cr₂O_Five, MnO₂, TiS₂, MoS₂Na
Which transition metal oxides and chalcogen oxides are proposed
ing.

In particular, Li _X CoO ₂ , Li _X NiO ₂ and Li _X
Mn ₂ O ₄ is promising as a positive electrode active material for 4V class non-aqueous electrolyte lithium batteries. Among these, Li _X NiO ₂ has the largest theoretical capacity, can be supplied inexpensively and stably, and is expected as a positive electrode active material for batteries.

As a method for converting these positive electrode active materials into sheet electrodes, as disclosed in JP-A-2-158055, a powdery active material, a conductive material, a carboxymethylcellulose (CMC) aqueous solution, and polytetrafluoroethylene. There is known a method in which the aqueous dispersion of (1) is uniformly mixed and applied on a film-shaped conductive foil such as rolled aluminum foil, dried, and rolled.

When a resin having excellent organic solvent resistance such as polytetrafluoroethylene or CMC is used as a binder for electrodes, ethylene carbonate (EC), propylene carbonate (PC) or diethyl used as an electrolyte solution solvent for lithium batteries. Since it does not swell or dissolve in an organic solvent such as carbonate (DEC) and the active material can be firmly bound, there is an advantage that good cycle characteristics as a battery can be realized. Especially, when the operating temperature of the battery becomes high, this difference becomes more remarkable.

Also, from the viewpoint of the electrode manufacturing process, by using such a water-dispersible resin or water-soluble resin, an organic solvent is not used in the manufacturing process, so that the solvent cost is reduced and the solvent cost is reduced. There are advantages such as reduction, no need for solvent recovery processing equipment, and reduction of industrial waste from battery manufacturing.

[0008]

[Problems to be Solved by the Invention] However, CMC
Since the binders such as the above also play a role as a thickener at the time of producing the electrode, it is necessary to add a certain amount or more. Therefore, it was found that the internal resistance (interfacial resistance) of the battery increases and the low-temperature output decreases.

In order to prevent such an increase in the internal resistance, the present invention uses a binder which can sufficiently act as a thickener and reduce the amount of use at the time of manufacturing an electrode, thereby providing a high output. It is an object to be solved to provide an electrode which can be a different battery and a battery using the electrode.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted extensive researches on various materials for the purpose of solving the above-mentioned problems and found that the water-soluble cellulose derivative partially substituted with a long-chain alkyl group satisfies the performance required. It was discovered that they did and completed the following invention.

That is, the electrode of the present invention has a current collector and a mixture layer containing an active material and a binder and formed on the current collector, wherein the binder is a long-chain alkyl group. It is characterized by being a water-soluble cellulose derivative containing.

The water-soluble cellulose derivative is preferably a compound having at least one of hydroxyethyl group and hydroxypropyl group.

A particularly preferred water-soluble cellulose derivative is a compound represented by the following general formula (1).

[0014]

[Chemical 2]

[R is an independently selected H, C
H₃, (CH₂CH₂O)_mR ', (CH ₂CH (CH₃)
O)_mR'and CH₂CH (OH) CH₂Of OR '
1, (R 'is independently H or has 18 or less carbon atoms
At least one of R'is a long chain alkyl group
Alkyl group)]] Furthermore, the battery of the present invention for solving the above-mentioned problems is
It is a battery using some of the electrodes.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the electrode and battery of the present invention will be described based on the electrode for a lithium secondary battery and the lithium secondary battery.

(Lithium Secondary Battery Electrode) The present electrode has a current collector and a mixture layer formed on the current collector, containing an active material capable of inserting and extracting lithium ions and a binder. . When the active material is the positive electrode active material, it may further include a conductive material such as a carbon material.

The binder is a water-soluble cellulose derivative containing a long chain alkyl group. Small amount of hydrophobic group (long-chain alkyl group)
In the aqueous solution, the water-soluble cellulose derivative into which is introduced forms a three-dimensional stitch structure by the association of hydrophobic groups. Therefore, it exhibits remarkably high water-soluble viscosity as compared with water-soluble cellulose having a similar molecular weight without introducing a hydrophobic group.
On the other hand, by having a hydrophobic group, it is considered to have an advantage of exhibiting higher surface activity and stabilizing the entire paste at the same time as adjusting the viscosity, as compared with the case of simply increasing the molecular weight of the water-soluble cellulose derivative. The long-chain alkyl group preferably has 18 or less carbon atoms. If the carbon number is too large, the hydrophobicity becomes large, which is not preferable. The ratio of introducing the long-chain alkyl group is within a range in which the binder made of the water-soluble cellulose derivative obtained can maintain water solubility.
As an example, in the case of a water-soluble cellulose derivative having a stearyloxyhydroxypropoxy group introduced, the long-chain alkyl group content is about 0.2 to 0.6% by mass. A binder having a longer-chain alkyl group introduced therein may not have sufficient water solubility.

The water-soluble cellulose derivative preferably has at least one of hydroxyethyl group and hydroxypropyl group. Water solubility can be imparted by these substituents. The hydroxyethyl group can be produced by reacting the hydroxy group of cellulose with ethylene oxide or ethylene glycol. The propylethyl group can be produced by reacting the hydroxy group of cellulose with ethylene oxide or ethylene glycol. The hydroxypropyl group is produced by reacting the hydroxy group of cellulose with propylene oxide or propylene glycol.
A hydroxyethyl group or a hydroxypropyl group may be further added to the hydroxy group at the tip of the hydroxyethyl group or hydroxypropyl group.

A particularly preferred water-soluble cellulose derivative is a compound represented by the following general formula (1).

[0021]

[Chemical 3]

[R is independently selected H, C
H₃, (CH₂CH₂O)_mR ', (CH ₂CH (CH₃)
O)_mR'and CH₂CH (OH) CH₂Of OR '
1, (R 'is independently H or has 18 or less carbon atoms
At least one of R'is a long chain alkyl group
Alkyl group)]] Explain specific preferred structure of water-soluble cellulose derivative
Then, as the binder, for example, hydroxyethylacetate is used.
Lulose with a small amount of long-chain alkyl group introduced, hydr
Roxypropyl methylcellulose with a small amount of long-chain alkyl
Group introduced (Sangelose 90L: Daido Kasei)
Water-soluble polymer materials such as Sangyo Co., Ltd., alone or in combination of two or more
A mixture of is used.

Further, water-soluble polymer materials such as methyl cellulose, ethyl cellulose, CMC, polyvinyl alcohol, polyethylene oxide, polyacrylic acid salts or polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene. -Perfluoroalkyl vinyl ether copolymer, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene-fluororesin such as perfluoroalkyl vinyl ether copolymer, acrylic resin, polyethylene, olefins such as polyolefin, It may be a mixture of water-dispersed resins having excellent organic solvent resistance such as polyimide resins.

As the active material, a positive electrode active material or a negative electrode active material is used depending on the electrode to be manufactured. The composition is not particularly limited.

The positive electrode active material preferably contains at least one lithium-containing composite oxide. The lithium-containing composite oxide has excellent performance as an active material such as excellent diffusion performance of electrons and lithium ions. Therefore, when such a composite oxide of lithium and a transition metal is used as a positive electrode active material, high charge / discharge efficiency and good cycle characteristics can be obtained. For example, Li _X Ni _(1-Y) M _Y
O ₂ (M is B, Mg, Ca, Sr, Ba, Ti, V, C
r, Mn, Fe, Co, Cu, Al, In, Nb, M
one or more elements selected from o, W, Y and Rh;
0.05 ≦ X ≦ 1.1, 0 ≦ Y ≦ 0.5) can be exemplified.

The positive electrode active material is more preferably one or more kinds of lithium-containing composite oxide having a layered structure. It is preferable to include a lithium nickel cobalt aluminum-containing composite oxide, a lithium manganese aluminum-containing composite oxide, or a lithium manganese chromium-containing composite oxide having a layered structure.

This is a constant voltage circuit (eg 4.2V).
In the case of charging and discharging at ~ 3V), since lithium-manganese-containing composite oxide having a spinel structure has a charging / discharging voltage biased toward the high potential side (average charging / discharging voltage: about 4V), high output density can be obtained by discharging However, while the regenerative density due to charging becomes smaller, the use of a layered material is thought to be the effect of structural changes during charging and discharging, but there is little bias in voltage due to charging and discharging (average voltage: It is possible to obtain a high output density and a high regenerative density with good balance. Further, it is more preferable that a part of the composition of the lithium nickel-containing composite oxide or the lithium manganese-containing composite oxide having a layered structure is replaced with another element such as aluminum or chromium. This is because deterioration of the inorganic positive electrode active material under a high temperature environment in which the electronic state inside the active material changes and the crystal structure is strengthened is reduced.

The positive electrode active material has a BET specific surface area of 1.5 m.
^{It is 2} / g or less, preferably 1.0 m ² / g or less. By setting the specific surface area to a certain value or less, a side reaction between the positive electrode active material and the electrolytic solution can be suppressed, so that the life can be extended. The method for controlling the specific surface area of the positive electrode active material is not particularly limited, but since the specific surface area is greatly influenced by the specific surface area of the raw material, it is possible to control by crushing and / or classifying the raw material under predetermined conditions. preferable. In addition, you may grind and / or classify after baking and producing.

The negative electrode active material is not particularly limited as long as it can store and release lithium ions. Known materials can be used. For example, carbon materials such as lithium metal, flaky graphite, spheroidal graphite, and amorphous carbon can be used. Further, an electrode formed of an intercalating material capable of electrochemically inserting and extracting lithium, particularly a carbon material is preferable. Since the negative electrode active material has a relatively large specific surface area and a high absorption / desorption rate, it is particularly suitable for output / regeneration density at room temperature.

The negative electrode active material has a BET specific surface area of 3.5 m ²
/ G or less, preferably 3.0 m ² / g or less. By setting the specific surface area to a certain value or less, a side reaction between the negative electrode active material and the electrolytic solution can be suppressed, so that the life can be extended. The method for controlling the specific surface area of the negative electrode active material is not particularly limited, but since the specific surface area is greatly influenced by the specific surface area of the raw material, it is possible to control by crushing and / or classifying the raw material under predetermined conditions. preferable. In addition, you may grind and / or classify after baking and producing.

The active material, the binder, and additives such as conductive materials that are added as necessary are mixed and dispersed in water to form a paste, and then a die coater, comma coater, reaper roller, doctor blade, etc. After applying with, dry
The electrode is manufactured by rolling. As the current collector, aluminum, stainless steel, etc. can be used for the positive electrode, and copper, nickel, etc. can be used for the negative electrode. They are used after being processed in the form of punched metal, foam metal or foil processed into a plate shape, respectively. it can.

(Lithium Secondary Battery) The lithium secondary battery electrode of this embodiment comprises a positive electrode, a negative electrode, an electrolytic solution and other necessary elements. The lithium secondary battery of the present embodiment is not particularly limited in its shape, and can be used as a battery of various shapes such as a coin type, a cylindrical type, and a square type. In the present embodiment, description will be made based on a cylindrical lithium secondary battery.

In the lithium secondary battery of the present embodiment, the positive electrode and the negative electrode are formed into a sheet shape, both are laminated with a separator, and a spirally wound body is wound a large number of times together with an electrolyte solution which fills the voids with a predetermined amount. It is stored in a cylindrical case. The positive electrode and the positive electrode terminal portion are electrically connected to each other, and the negative electrode and the negative electrode terminal portion are electrically connected to each other.

At least one of the positive electrode and the negative electrode uses the electrode of this embodiment described above. In particular, it is preferable to use the electrode of this embodiment for both the positive and negative electrodes.

The electrolytic solution is a solution of an electrolyte in an organic solvent.

The organic solvent is not particularly limited as long as it is an organic solvent usually used in an electrolytic solution of a lithium secondary battery, and examples thereof include carbonates, halogenated hydrocarbons, ethers, ketones, nitriles and lactones. , Oxolane compounds and the like can be used. In particular, propylene carbonate, ethylene carbonate, 1,2-dimethoxyethane, dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate, vinylene carbonate and the like and mixed solvents thereof are suitable.

Of these organic solvents listed as examples, one selected from the group consisting of carbonates and ethers
It is preferable to use at least one kind of non-aqueous solvent because the solubility, the inductivity and the viscosity of the electrolyte are excellent and the charge / discharge efficiency of the battery is increased.

The type of electrolyte is particularly limited.
But not LiPF₆, LiBF_Four, LiClO_Fouras well as
LiAsF₆Inorganic salts selected from
Body, LiSO₃CF₃, LiC (SO₃CF₃)₂And Li
N (SO₂CF₃)₂, LiN (SO ₂C₂F₆)₈, LiN
(SO₂CF₃) (SO₂C_FourF₉) Etc. organic
A salt and at least one derivative of the organic salt
And is desirable.

By this electrolyte, the battery performance can be further improved, and the battery performance can be maintained even higher in a temperature range other than room temperature.

The concentration of the electrolyte is not particularly limited, and it is preferable to properly select it in consideration of the types of the electrolyte and the organic solvent according to the use.

The separator plays a role of electrically insulating the positive electrode and the negative electrode and holding the electrolytic solution. For example, a porous synthetic resin film, particularly a porous film of polyolefin polymer (polyethylene, polypropylene, etc.) may be used. The separator is preferably larger than the positive electrode and the negative electrode in order to ensure the insulation between the positive electrode and the negative electrode.

The case is not particularly limited,
It can be made of a known material and form.

The gasket ensures electrical insulation between the case and both terminal portions of the positive electrode and hermeticity in the case. For example, the electrolyte may be composed of a polymer such as polypropylene that is chemically and electrically stable.

[0044]

EXAMPLES The following are specific examples of the present invention.

(Measurement of low temperature output ratio) 18
A 650 size battery was prototyped and the charging current was 250 at the first time.
CC-CV charging was performed up to 4.1 (V) at (mA), and CC discharging was performed up to 3.0 (V) at discharging current 333 (mA). Next, CC-CV charging up to 4.1 (V) at a charging current 1000 (mA), 3.0 at a discharging current 1000 (mA).
Conditioning was performed by performing 4 cycles of CC discharge up to (V). Then, the output characteristics were evaluated using the batteries of each test example. First, the battery is charged at a constant current of 992 (mA) at room temperature, and the battery's state of charge SO
C (State of Charge) was adjusted to 60%. Then, at low temperature (-30 ° C), the operating voltage range of the battery was changed from 4.1V to 3.0V, the discharge current of the battery was changed, and the discharge current was changed for 10 seconds. − A voltage straight line was obtained, and the value of the output characteristic was calculated from the voltage straight line.

Example 1 As the battery of Example 1, a cylindrical lithium secondary battery in which the positive electrode active material or the negative electrode active material was changed was produced. Here, the lithium secondary battery manufactured in the example is shown in FIG.

This cylindrical lithium secondary battery 100 has a positive electrode 1 having a positive electrode active material containing lithium, capable of releasing lithium as lithium ions during charging and occluding lithium ions during discharging, and a carbon material. A negative electrode 2 having the following negative electrode active material, capable of occluding lithium ions during charging and releasing lithium ions during discharging, and a non-aqueous electrolytic solution 3 formed by dissolving an electrolyte containing lithium in an organic solvent, A lithium secondary battery including a separator 4 disposed between a positive electrode and a negative electrode.

The positive electrode 1 includes a positive electrode current collector 11 made of aluminum, a positive electrode mixture layer 12 having a positive electrode active material and a binder formed on the surface of the positive electrode current collector 11, and a positive electrode current collector. The positive electrode current collector lead 13 joined to the electrode is formed into a sheet shape.

The negative electrode 2 includes a negative electrode current collector 21 made of copper,
An electrode composed of a negative electrode mixture layer 22 having a negative electrode active material and a binder formed on the surface of the negative electrode current collector 21, and a negative electrode current collection lead 23 joined to the negative electrode current collector 21. , Formed in a sheet shape.

The positive electrode 1 and the negative electrode 2 are held in the case 7 in a state of being wound with a sheet-shaped separator 4 interposed therebetween. Further, the current collecting leads 1 for the positive electrode 1 and the negative electrode 2
Reference numerals 3 and 23 are connected to the positive electrode terminal portion 5 and the negative electrode terminal portion 6 of the case 7, respectively.

As the separator 4, a microporous polyethylene film having a thickness of 25 μm was used.

The electrolytic solution was prepared by mixing LiPF ₆ as an electrolyte with 1 m of a solvent prepared by mixing ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of 3: 7.
A solution dissolved at a ratio of ol / L was used.

The lithium secondary battery of the example was manufactured by the following procedure.

(Production of Positive Electrode) The composition of the positive electrode active material is L
i _0.8 Co _0.15 Al _0.05 O ₂ 87 parts by mass of lithium nickel oxide, 10 parts by mass of acetylene black (product number: HS-100) as a conductive material, and Sangelose 90L as a binder (Daido Kasei) Industrial Co., Ltd. 1
The mixture was mixed at a ratio of parts by mass, and stirred with a twin-screw stirrer for 1 hour. After that, PTF with a solid content ratio of 50% as a binder
E aqueous dispersion was added so that the solid content of PTFE was 2 parts by mass, and the mixture was stirred for 30 minutes using a vacuum emulsification stirring device. The obtained paste is applied on both sides of an aluminum foil with a comma coater at a basis weight of 8.56 (mg / cm ² ) per side. Then pass this electrode through a roll press machine,
Linear pressure 7.4 × 10 ⁴ kg / m (0.74 (ton / c
m)) is applied and the electrode density is 2.41 (g / cm ² ).
And Next, this electrode was cut into a width of 5.4 cm and a length of 86 mm, and an electrode mixture layer having a length of 2.5 cm was scraped off as a lead tab weld for current extraction. The effective reaction area of this electrode is 901.8 cm ² .

(Manufacture of Negative Electrode) 92.5 parts by mass of scaly graphite as a negative electrode active material and PVDF as a binder
Was mixed at a ratio of 7.5 parts by mass, PVDF was dissolved in N-methyl-2-pyrrolidone, and then graphite was dispersed to prepare a paste. The obtained paste was applied on a copper foil with a comma coater to give a basis weight of 5.1 (mg / cm
² ) Apply on both sides. Next, this electrode is passed through a roll press to obtain a linear pressure of 2.5 × 10 ⁴ kg / m (0.25 (ton
/ Cm)) and the electrode density is 1.25 (g / cm).
² ) Next, this electrode was formed with a width of 5.6 cm and a length of 90.
It was cut into 5 mm, and an electrode mixture material layer having a length of 0.5 cm was scraped off as a lead tab weld portion for extracting current. The effective reaction area of this electrode is 1008 cm ² .

(Assembly of Battery) The sheet-like positive electrode and sheet-like negative electrode obtained above were wound with a separator (made of polyethylene, thickness 25 μm) interposed therebetween to form a wound electrode body. The obtained wound electrode body was inserted into the case and held in the case. At this time, the current collecting lead having one end welded to the lead tab weld portion of the sheet-shaped positive electrode and the sheet-shaped negative electrode was joined to the positive electrode terminal or the negative electrode terminal of the case.

After that, an electrolytic solution in which an electrolyte is dissolved in an organic solvent is injected into the case holding the spirally wound electrode body,
The case is hermetically sealed.

By the procedure described above, a cylindrical lithium secondary battery having a diameter of 18 mm and an axial length of 65 mm was manufactured.

(Example 2) The battery of this example had the same composition as in Example 1 except that 1 part by mass of hydrophobic hydroxyethyl cellulose (average degree of polymerization of about 30,000) as a water-soluble cellulose derivative was used as a binder. , A battery was manufactured by the method.

Comparative Example 1 A battery of this comparative example was manufactured by the same composition and method as in Example 1 except that 1 part by mass of Sangelose 90M was used as a binder.

(Comparative Example 2) The battery of this comparative example has hydroxyethyl cellulose (average degree of polymerization of about 3000) as a binder.
A battery was manufactured with the same composition and method as in Example 1, except that 1 part by weight of 0) was used.

Comparative Example 3 The battery of this Comparative Example was the same as Example 1 except that 2 parts by mass of hydroxypropylmethyl cellulose (average degree of polymerization of about 30,000) and 1 part by mass of PTFE solid content were used as the binder. A battery was manufactured with the composition and method described in 1.

Comparative Example 4 The battery of this Comparative Example was manufactured by the same composition and method as in Example 1 except that 1 part by mass of the same hydroxypropylmethyl cellulose as in Comparative Example 3 was used as the binder.

Table 1 shows the methoxy group and hydroxypropoxy group in the chemical formulas of the binders used in each of the examples and comparative examples.
The content ratio of a hydroxyethoxy group and a stearyloxy hydroxypropoxy group (long-chain alkyl group) is shown.

[0065]

[Table 1]

(Results) The binders used in Comparative Examples 1 and 2 were too high in content of long-chain alkyl groups to be dissolved in water, so that electrodes could not be manufactured. Although the binders used in Comparative Examples 3 and 4 are water-soluble, it is necessary to add 2 parts by mass (Comparative Example 3) in order to obtain a viscosity of the aqueous solution sufficient to prepare an electrode. The electrode could not be created.

Comparing the viscosity ratios of the pastes of Examples 1 and 2 and Comparative Example 3 in which the electrodes could be prepared, the viscosity of the paste is as follows:
Was 2. Further, the low temperature output ratio was 2.5 for Example 1 and 2 for Example 2 when the low temperature output of Comparative Example 3 was 1.

As described above, in the battery using the electrode of this example, the use ratio of the binder can be reduced, so that the internal resistance of the electrode can be reduced and the low temperature output can be increased.

[0069]

By using the electrode of the present invention and the electrode produced by the present production method in a battery, the low temperature output is improved. Further, the lithium secondary battery of the present invention has a high low-temperature output, and thus is a particularly useful battery when a large current is required.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a cylindrical lithium secondary battery produced in an example.

[Explanation of symbols]

100 ... Lithium secondary battery 1 ... Positive electrode 11 ... Positive electrode current collector 12 ... Positive electrode mixture layer 13 ... Current collecting lead 2 ... Negative electrode 21 ... Negative electrode current collector 22 ... Negative electrode mixture layer 23 ... Current collecting lead 3 ... Electrolyte 4 ... Separator 5 ... Positive electrode terminal portion 6 ... Negative electrode terminal portion 7 ... Case

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5H029 AJ06 AK03 AL06 AL12 AM03                       AM04 AM05 AM07 BJ02 BJ14                       DJ08 EJ12 HJ02                 5H050 AA12 BA17 CA07 CB07 CB12                       DA11 EA25 FA05 HA02

Claims (4)

[Claims] 1. A water-soluble cellulose derivative having a current collector and a mixture layer containing an active material and a binder and formed on the current collector, wherein the binder contains a long-chain alkyl group. An electrode characterized by: 2. The electrode according to claim 1, wherein the water-soluble cellulose derivative has at least one of a hydroxyethyl group and a hydroxypropyl group. 3. The water-soluble cellulose derivative has the following formula:
The electrode according to claim 2, which is represented by the general formula shown in (1). [Chemical 1] [R is independently selected H, CH₃, (CH₂
CH₂O)_mR ', (CH ₂CH (CH₃) O)_mR'and
CH₂CH (OH) CH₂One of the OR's (R 'is
Each independently H or long chain alkyl having 18 or less carbon atoms
At least one of the groups R'is a long-chain alkyl group.
)] 4. A battery having the electrode according to claim 1.