JP6528972B2 - Nickel-based secondary battery - Google Patents

Description

  The present invention relates to a nickel secondary battery.

  A battery generally includes, as components, both positive and negative electrodes, a separator that separates them, and an electrolyte solution that has spread throughout the battery. The positive electrode and the negative electrode each contain an active material. The negative electrode active material has a property of passing electrons to the positive electrode active material, and at the time of discharge, a current flows by transferring electrons from the negative electrode active material to the positive electrode active material through an external circuit. That is, at the time of discharge, the negative electrode active material is oxidized and the positive electrode active material is reduced. On the other hand, when the electrolyte conducts ions between the positive and negative electrodes, a steady current can be obtained as a system. Further, the separator is for preventing direct contact of both positive and negative active materials, that is, for preventing short circuit. When charging the secondary battery, an external voltage is applied to cause the opposite electron transfer. That is, at the time of charge, the negative electrode active material is reduced and the positive electrode active material is oxidized.

As seen in the recent spread of portable devices, the spread of hybrid vehicles against the background of environmental and energy problems, or the development of stationary large batteries for storage of electric vehicles and surplus power, etc. The role they play and their expectations are growing. In particular, the significant improvement of fuel efficiency by hybrid vehicles has a great effect on environmental and energy problems such as CO ₂ emission reduction and oil resource saving as well as user cost saving. In the future, as batteries are improved and electric vehicles are spread, it will be possible to reduce fundamental emissions of CO ₂ and energy shift independent of fossil fuels, which will further affect environmental and energy problems. Can be expected. Although these automobile-related fields originally have large energy consumption and have a large impact on the environment and energy, in addition to basic properties such as energy density, high current charge performance, durability, etc., batteries for automotive use Strict performance conditions such as ease are required, and further improvement is desired.

A nickel hydrogen battery, which is one of the representative secondary batteries, uses a nonflammable aqueous electrolyte, and hydrogen of the negative electrode active material itself is not a metal, so shorts are less likely to occur, and further relatively rapidly at constant current Even if the battery is fully charged, it is a battery that is relatively safe and easy to control charging, such as when the battery is fully charged, the electrolysis of water in the electrolyte is automatically replaced to suppress the voltage rise. At present, nickel hydrogen batteries are widely used as batteries for hybrid vehicles. Nickel-metal hydride batteries use a hydrogen storage alloy for the negative electrode, nickel hydroxide for the positive electrode, and an alkaline electrolyte as the electrolyte. As shown in the following equations (1) and (2), the negative electrode uses water during charging. The electrochemical reduction of molecular hydrogen and the storage of hydrogen in the hydrogen storage alloy occur, and the electrochemical oxidation of the stored hydrogen occurs conversely at the time of discharge.
[Charging] H ₂ O + e ⁻ → H (occluded) + OH ⁻ (1)
[Discharge] H (storage) + OH ⁻ → H ₂ O + e ⁻ (2)
As a hydrogen storage alloy, one mainly composed of an alloy of rare earth and nickel is mainly used.

At the positive electrode, as shown in the following equations (3) and (4), an electrochemical redox reaction of nickel hydroxide or nickel oxyhydroxide occurs.
[Charging] Ni (OH) ₂ + OH ⁻ → NiOOH + H ₂ O + e ⁻ (3)
[Discharge] _{NiOOH + H 2 O + e- →} Ni (OH) 2 + OH - ··· (4)

As a battery using a positive electrode using such nickel hydroxide or nickel oxyhydroxide, there are a nickel-iron battery, a nickel-zinc battery and the like as well as a nickel-hydrogen battery. In the former, the negative electrode of a nickel-metal hydride battery is replaced by an iron electrode (see the following formulas (5) and (6)),
[Charging] ^{_{Fe (OH) 2 + 2e -}} → Fe + 2OH - ··· (5)
[Discharge] ^{Fe + 2OH - → Fe (OH} ) 2 + 2e - ··· (6)
The latter is replaced with a zinc electrode (see the following equations (7) and (8)).
[Charging] ZnO + H ₂ O + 2 e ⁻ → Zn ₂ + 2 OH ⁻ (7)
[Discharge] ^{Zn + 2OH - → ZnO + H} 2 O + 2e - ··· (8)

  Conventionally, spherical high density nickel hydroxide is generally used as the active material for the positive electrode nickel electrode. The spherical high-density nickel hydroxide is one in which primary particles are densely aggregated to form secondary particles in a spherical shape, and high-density filling of the active material to the electrode becomes possible, and the battery capacity is increased. be able to. Spherical high-density particles are prepared by aging nickel hydroxide in a solution having a slight solubility in nickel hydroxide, which contains a complex-forming agent such as ammonia, for example, when synthesizing nickel hydroxide. Ru. That is, the initially amorphous nickel hydroxide is also preferentially dissolved from the corner portion with high solubility during ripening, and the corner is taken off and the melted one precipitates in the pores of the particles. As this is repeated, the particles change to spherical densities. In this process of ripening, crystals (primary particles) in the particles also grow.

Nickel hydroxide and nickel oxyhydroxide are layered compounds, and the conventional spherical high-density nickel hydroxide prepared through the above-mentioned ripening process forms particularly distinct layered crystals. Nickel hydroxide at the time of synthesis has a stable β-type nickel hydroxide structure, and the composition is also substantially Ni (OH) ₂ . On the other hand, nickel oxyhydroxide that has been charged (oxidized) by charging has a high valence number of Ni as shown in equation (3), and protons (hydrogen ions) are eliminated to become NiOOH. Instead, in order to ease the densification of the electric field due to the increase in the number of Ni, the layers are opened, and water molecules of the electrolyte solution, potassium hydroxide, sodium hydroxide, lithium hydroxide and the like are intercalated between the layers. In particular, in a highly charged Ni electrode, the valence number of Ni becomes very high, and as a result, the interlayer may be widely opened, and a γ-type structure in which many water molecules and ions are intercalated between the interlayer may be taken. The γ-type nickel oxyhydroxide has a low charge / discharge potential, has an action to lower the battery voltage, and has a low activity for charge / discharge reaction. In addition, when a large amount of γ-type nickel oxyhydroxide is formed, a large amount of water of the electrolytic solution is absorbed and fixed to the nickel electrode, and the volume of the nickel electrode itself is also significantly increased. It causes the separator to dry up and affects the battery life. As described above, the γ-type conversion of nickel oxyhydroxide has an undesirable effect on a battery, and in order to suppress this, conventional nickel hydroxide substitutes zinc with part of nickel (solid solution) in order to suppress this. Things were well done.

  In addition, nickel hydroxide itself has no electron conductivity, and the progress of charge / discharge reaction is very slow especially at the end of discharge, so conventional nickel hydroxide is a nickel nickel hydroxide in order to supplement its electron conductivity. Generally, cobalt substitution (solid solution) in the part or coating of cobalt oxide on the surface of nickel hydroxide particles has been performed. It is also effective to add a divalent cobalt compound such as cobalt oxide into the nickel electrode, and when the electrolyte is injected into the battery, the cobalt dissolves, and when it is charged thereafter, the cobalt is oxidized and becomes insoluble. Therefore, the nickel hydroxide surface is automatically coated with cobalt.

  As described above, various problems inherent to the nickel electrode are being improved in the process up to the present. However, one major problem that has not been solved even now is the memory effect. Nickel-metal hydride batteries currently used in hybrid vehicles etc. are fully discharged and fully charged when used in a small amount of charge and discharge, that is, with a slight discharge and a slight charge. It exhibits anomalous voltage behavior different from the charge and discharge voltage when it is used. This phenomenon is generally referred to as a memory effect because the voltage behavior changes depending on how the battery is used, which makes it difficult to control the battery and therefore has a problem that the battery's inherent capability can not be used up. In portable devices etc., it is possible to prevent the user to perform deep charge and discharge to some extent, but the use in the hybrid car is originally used always to perform small charge and discharge in the intermediate charge state. Expression is inevitable.

  This memory effect is due to the nickel electrode and is closely related to the layer structure of nickel hydroxide or nickel oxyhydroxide. For example, in Patent Document 1, it is important that almost no change in the c-axis length (layer spacing) of nickel hydroxide occurs when left in a fully discharged state, and trivalent or more such as tungsten, niobium, zirconium, etc. A method in which a cation is dissolved in nickel hydroxide to reduce the amount of solid solution of divalent cations other than nickel is said to be effective for suppressing the memory effect.

  On the other hand, regarding the negative electrode, conventionally, a nickel-based alloy (such as LaNi5) containing misch metal mainly composed of rare earths is generally used as a negative electrode active material of a nickel-based battery. The adsorption / desorption equilibrium pressure of hydrogen on this nickel-based alloy is near normal pressure, and the above-mentioned charge / discharge can be performed without pressurizing / depressurizing the inside of the battery. It is a composition. Furthermore, various metal elements (eg, Mn, Mg, Al, Zr, Co, etc.) are generally added to impart stability and electron conductivity thereto.

  However, rare earths are primarily expensive due to their small abundance. Also, there is a problem that the price tends to fluctuate due to political problems and stable and inexpensive supply can not be expected in the future, because the producing countries are also limited to countries with high geopolitical risk. In addition, extraction is difficult, and there are many environmental concerns as it passes through a large number of chemical processes at present.

  Thus, in response to the problems of the nickel-based alloy negative electrode, an inexpensive and abundant negative electrode material mainly composed of iron has been proposed in the United States over 100 years ago. When an iron electrode is used in a battery, the battery exhibits a potential close to that of a hydrogen storage alloy electrode which is a negative electrode of a nickel hydrogen battery, and has a larger theoretical capacity. However, when a normal iron material is used, there is a problem that passivation occurs on the particle surface and charging and discharging can not be performed. There are only a few cases that have been put to practical use in practice, but the gas generated during charge and discharge needs to be released to the outside, and it is necessary to add electrolytes, and maintenance and durability are difficult. It has not spread.

  Besides iron electrodes, zinc electrodes using zinc oxide have been proposed. When a zinc electrode is used in a battery, a battery with higher energy density can be formed. However, zinc oxide is easily dissolved in an alkaline electrolyte, and needle zinc (dendrite) is formed when the eluted zinc ions are reduced during charging, which causes problems such as penetration of the separator to cause a short circuit. After all, practical application is difficult.

  On the other hand, those based on inorganic / organic hybrid compounds in which a zirconate compound and polyvinyl alcohol are chemically bonded can be used for alkaline batteries such as nickel hydrogen batteries, and are solid because they have hydroxide ion conductivity. It is disclosed that it can play a role as an electrolyte, or can provide various other functions (see Patent Documents 2, 3, 4 and 5). For example, by applying these inorganic / organic hybrid compounds, it is possible to contribute to the decrease in the amount of electrolyte solution of the nickel hydrogen battery, and to thin the separator by the short circuit preventing function. Further, according to Patent Documents 2 and 3, these inorganic / organic hybrid compounds can be subjected to a treatment of immersing in an alkaline aqueous solution, that is, a treatment of absorbing an alkaline aqueous solution to obtain high hydroxide ion conductivity. It is disclosed.

  As a method of obtaining an inorganic / organic hybrid compound in which the zirconate compound and the polyvinyl alcohol are chemically bonded, Patent Documents 2 and 3 disclose that a zirconium salt or an oxyzirconium salt is neutralized in a solution in which polyvinyl alcohol coexists, A method of removing is disclosed. Further, in Patent Documents 4 and 5, a solid in which a zirconium salt or an oxyzirconium salt and a polyvinyl alcohol coexist is previously formed, and the solid is brought into contact with an alkali to neutralize the zirconium salt or the oxyzirconium salt. A method is disclosed.

JP, 2014-049210, A Patent No. 3848882 Specification Patent No. 4081343 Patent No. 5095249 specification Patent No. 4871225 specification

  As in the memory effect, if the curve of the battery voltage changes depending on the conditions used, it causes problems in battery control. When the working voltage range of the battery is set, for example, even if the battery is not fully discharged, it may be judged as the discharge limit, or even if it is not sufficiently charged, the charge may be ended. Happens. Especially in a hybrid car, it is easy to use memory effect because it is used repeatedly in small charge and discharge in the middle charge state at all times, and it is difficult to grasp the charge state from the voltage if the voltage changes due to the memory effect By controlling the voltage to a certain reference voltage, it becomes difficult to return the charge state to the reference state. Therefore, in order to allow the use of the battery, the use voltage range has been narrowed to a safe range, and the use condition has been such that the original battery capacity is not sufficiently utilized. For this reason, memory effect suppression is particularly important in automotive applications.

  By the way, the existence of slow processes such as expansion / contraction between layers and insertion / extraction of interlayer materials, which is the core of the phenomenon of the memory effect, means that various substance states (substance types) exist in the electrode active material. This means that the flatness of the charge / discharge voltage curve is deteriorated. That is, a substance susceptible to discharge is discharged at a higher voltage, and a substance in a state difficult to discharge is discharged at a lower voltage, resulting in a large change in voltage during the discharge. Also, materials that are easy to charge are charged at lower voltages, and materials that are difficult to charge are charged at higher voltages, resulting in large voltage changes during charging. Poor flatness of the charge / discharge voltage curve leads to a decrease in discharge characteristics at the end of discharge, a decrease in charge efficiency at the end of charge, a decrease in stored energy utilization efficiency, and the like. In the conventional nickel electrode active material, a layered crystal is grown, and there is a material state (material type) with different strengths between layers, so the flatness of the charge / discharge voltage curve is not good.

In hybrid vehicles, batteries are used in a manner that repeats small amounts of charge and discharge, but if the balance of charge and discharge amounts is finely integrated, it should be possible to grasp the charge state at that time. However, if the charge efficiency is not 100% or self discharge occurs during use, the actual charge state deviates from that predicted from the charge / discharge integrated capacity. Therefore, the voltage changes as the state of charge gradually shifts during use. This again makes the control of the battery difficult.
At that time, if the charge / discharge voltage curve is flat, the voltage change due to the deviation of the charge state can be reduced. In addition, the voltage change due to the deviation of the charge state can sometimes be returned by controlling the voltage to the reference value and returning the charge state to the reference state.

However, in the conventional nickel electrode active material, since the charge / discharge voltage curve is not flat, the voltage changes significantly. Further, since the battery using the conventional nickel electrode has a large memory effect, there is no guarantee that the state of charge returns to the intended reference state even if the voltage is controlled to the reference value.
As described above, the memory effect of the nickel hydrogen battery is due to the layered structure of the nickel hydroxide or oxyhydroxide nickel of the positive electrode. In the positive electrode, when the nickel atom is discharged and the nickel atom is in the divalent or near state, the closed β-Ni (OH) ₂ phase between the layers is thermodynamically stable but the nickel is charged more At high valences, the layers are opened to relieve the high electric field of the nickel atom, and the state in which water molecules having a high dielectric constant are inserted therein is rather thermodynamically stable. Therefore, expansion / contraction between layers and intercalation / desorption of interlayer materials should normally proceed with charge and discharge, but this process is very slow, such as large intramolecular migration of water molecules.

  Therefore, for example, when deep charging and discharging are performed and the state of charge largely changes in a relatively short time, expansion / contraction between layers and insertion / release of interlayer substances can not be completely followed, and an intermediate quasi In the steady state, only the valence of nickel changes significantly. There is a significant difference between the charge and discharge potential of the nickel electrode when such deep charge and discharge is performed and the potential when expansion and contraction of the layer and insertion and detachment of the interlayer material occur sufficiently. On the other hand, when only a small amount of charge and discharge is performed, the change in the charge state is small, and if there are places in the electrode where charge and discharge reactions are likely to occur and places where it is unlikely to occur, reactions are concentrated at places where charge and discharge reactions are likely to occur. In places where reaction is unlikely to occur, the state of charge will not change further. In this way, in the portion where the reaction of the nickel electrode active material is less likely to occur, the time for transition to a stable state is given by expansion / contraction between layers and insertion / removal of interlayer material. In that case, the nickel electrode potential is different from when deep charging and discharging are performed. Thus, since the nickel electrode potential is different depending on the contents of charge and discharge, a memory effect is produced.

Assuming that the memory effect is caused by such a mechanism, as in Patent Document 1, a situation in which a cation having a valence of 3 or more is introduced into nickel hydroxide to reduce divalent cations and not close the interlayer. If it is possible, it may be possible to suppress the memory effect. However, in order to prevent the interlayer from being closed, it is necessary to form a solid solution of a trivalent or higher cation, but the conventional nickel hydroxide for a battery is subjected to a ripening step for the purpose of spherical densification. Thus, there is a limit to the solid capacity of the different cations, as it is highly crystallized and proceeds to the higher purity of nickel hydroxide.
On the other hand, even if trivalent or higher cations can be solid-solved in large amounts without undergoing the aging step, they are components that do not contribute to charge and discharge, and the capacity of the nickel electrode is greatly reduced.
Moreover, although the method of introduce | transducing the cation with high valence can suppress that an interlayer closes by the low charge side, it is difficult to prevent that an interlayer opens large by the high charge side.
Therefore, the memory effect can not be sufficiently suppressed by the method as in Patent Document 1.

  On the other hand, theoretically, if nickel hydroxide or nickel oxyhydroxide has a very low crystallinity, more random structure, or an amorphous structure, the layer structure can not shift to a completely stable state, and memory The effect can be made hard to appear. Furthermore, for example, fine particles such as nanoparticles can not form a stable layer structure, so that the memory effect can be more fundamentally suppressed.

The battery active material containing nickel hydroxide, nickel oxyhydroxide or derivatives thereof which are fine particles such as low crystallinity, amorphous or nanoparticles, for example, precipitates nickel hydroxide in a liquid phase using a nickel salt as a raw material It can not be manufactured by the general method of In particular, as described above, the conventional general nickel hydroxide for battery is one in which a layered crystal is more grown through the aging step. Therefore, it is difficult to realize nickel hydroxide, nickel oxyhydroxide or their derivatives, which are particles of sufficiently low crystallinity, amorphous or nanoparticles such as nanoparticles, without special manufacturing methods.
Also, even if a certain degree of low crystallinity, amorphous or fine particles are produced, these substances are originally unstable and change to more stable crystals, and fine particles such as nanoparticles aggregate. Furthermore, it is easy to grow. For example, fine particles such as nanoparticles are often stored in a liquid in order to prevent aggregation, but aggregation will occur at the time of electrode formation. In some cases, crystallization may be progressed while the low crystalline or amorphous electrode active material is repeatedly charged / discharged, that is, while it is undergoing a violent substance change such as an oxidation reaction and a reduction reaction.

However, as a result of intensive studies by the present inventors, by causing the produced fine particles to coexist with another stable substance, the aggregation and growth of the fine particles are prevented, and the low crystalline, amorphous or fine particles such as nanoparticles are stabilized. It turned out that it can maintain. Specifically, by causing a polymer having resistance to a strong alkali of the electrolytic solution without causing a redox reaction in the electrode working potential range and fine particles of nickel hydroxide, nickel oxyhydroxide or derivatives thereof, It has been found that a positive electrode active material containing nickel hydroxide, nickel oxyhydroxide, or derivatives thereof which are fine particles such as low crystallinity, amorphous or nanoparticles is obtained.
However, such a positive electrode active material is considered to have points to be improved with respect to the electron conductivity. Basically, the electron conductivity of both Ni (OH) ₂ and NiOOH is extremely low, and according to the literature, the former is about 10 ^-12 S / cm at room temperature and the latter is about 10 ^-8 S / cm. is there. Here, it is expected that the incorporation of the insulating polymer lowers the electron conductivity.

On the other hand, in the case of using an iron element for the negative electrode, the formation of stable passive Fe (OH) ₂ in an alkaline atmosphere is a major problem in using it as the negative electrode. Although methods of adding chalcogenide elements such as sulfur have been reported in order to prevent this passivation, the elution of those elements may poison the active material of the battery and is not recommended.

  On the other hand, theoretically, if iron hydroxide or pure iron has a very low crystallinity, a more random structure, or an amorphous structure, the particle surface can not shift to a completely stable state, and passivity is It can be difficult to form. Furthermore, if the particles are as fine as, for example, nanoparticles, stable structures can not be formed, and thus passive formation can be more effectively suppressed.

  However, conventional general iron hydroxides for batteries are small in particle size even at the micron level, and iron hydroxide, iron oxyhydroxide or their particles which are sufficiently low in crystallinity, amorphous or nanoparticles such as nanoparticles. Similar to the above-mentioned nickel hydroxide and the like, it is difficult to realize their derivatives without special manufacturing methods.

  However, as a result of intensive studies by the present inventors, by causing the produced fine particles to coexist with another stable substance, the aggregation and growth of the fine particles are prevented, and the low crystalline, amorphous or fine particles such as nanoparticles are stabilized. It turned out that it can maintain. Specifically, by causing a polymer having resistance to a strong alkali of the electrolytic solution without causing a redox reaction in the electrode working potential range and fine particles of iron hydroxide, iron oxyhydroxide or derivatives thereof, It has been found that a negative electrode active material containing iron hydroxide, iron oxyhydroxide or derivatives thereof which are fine particles such as low crystallinity, amorphous or nanoparticles is obtained.

However, such a negative electrode active material is considered to have a point to be improved with respect to the electron conductivity. Basically, the electron conductivity of Fe (OH) ₂ alone is extremely low, and according to the literature, the former is approximately 10 ^-12 S / cm at room temperature. It is expected that the electronic conductivity will be further reduced by further incorporating an insulating polymer here.

Although the iron element has been described above, the same can be said for the prevention of dendrite even with zinc element, and as a result of intensive investigations by the present inventors, aggregation of the microparticles is achieved by causing the produced microparticles to coexist with another stable substance. It has been found that it is possible to prevent growth and stably maintain fine particles such as low crystallinity, amorphous or nanoparticles. Specifically, by causing a polymer having resistance to a strong alkali of an electrolytic solution without causing a redox reaction in the electrode working potential range and fine particles of zinc oxide to coexist, it is low in crystallinity, amorphous or like nanoparticles. It has been found that a negative electrode active material containing zinc oxide, which is a fine particle, can be obtained.
It is considered that there is a point to be improved with respect to the electron conductivity also for such a negative electrode active material.

  Then, an object of the present invention is to provide a nickel-based secondary battery which overcomes various improvement points of the active material of the nickel-based secondary battery.

The nickel-based secondary battery disclosed herein comprises a positive electrode, a negative electrode, and an electrolyte. The nickel-based secondary battery satisfies one or both of the following conditions (A) and (B).
(A) The positive electrode includes a positive electrode active material containing at least one selected from nickel hydroxide, nickel oxyhydroxide, and derivatives thereof, and an electron conductive material dispersed in the positive electrode active material; In the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using CuKα ray when the substance is in the state containing nickel hydroxide, the diffraction peak intensity corresponding to the crystal 001 plane of nickel hydroxide The half width is 2 (2θ °) or more, or there is no diffraction peak.
(B) The negative electrode includes a negative electrode active material containing at least one selected from iron hydroxide, iron oxyhydroxide, zinc oxide, and derivatives thereof, and an electron conductive material dispersed in the negative electrode active material, In the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using CuKα radiation when the negative electrode active material contains iron hydroxide or zinc oxide, crystals of iron hydroxide or zinc oxide The half value width of the diffraction peak intensity corresponding to the 001 plane is 2 (2θ °) or more, or there is no diffraction peak.

According to such a configuration, it is possible to provide a nickel-based secondary battery that overcomes various improvements in the active material of the nickel-based secondary battery.
Specifically, when a nickel-based secondary battery satisfies the condition (A), diffraction obtained by powder X-ray diffraction using CuKα rays when the positive electrode active material contains nickel hydroxide In the intensity-diffraction angle diagram, the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of nickel hydroxide is 2 (2θ °) or more, or that there is no diffraction peak, nickel hydroxide, nickel oxyhydroxide or The memory effect is suppressed and a flat charge / discharge potential curve can be obtained, since it indicates that the derivatives are actually in the state of fine particles such as low crystallinity, amorphous or nanoparticles. In addition, since the positive electrode contains an electron conductive material, the electron conductivity also becomes good.
In the case where the nickel-based battery satisfies the condition (B) and the negative electrode is an iron electrode, powder X-ray diffraction using CuKα radiation when the negative electrode active material contains iron hydroxide In the diffraction intensity-diffraction angle diagram obtained by the method, the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of iron hydroxide is 2 (2θ °) or more, or there is no diffraction peak. Since the iron oxyhydroxide or a derivative thereof actually represents a sufficiently low crystalline, amorphous or fine particle state such as nanoparticles, the formation of passive state can be suppressed. In addition, since the negative electrode contains an electron conductive material, the electron conductivity also becomes good.
In the case where the nickel-based battery satisfies the condition (B), and the negative electrode is a zinc electrode, powder X-ray diffraction method using CuKα radiation when the negative electrode active material becomes a state containing zinc oxide In the diffraction intensity-diffraction angle diagram obtained in 2, the half-width of the diffraction peak intensity corresponding to the crystal 001 plane of zinc oxide is 2 (2θ °) or more, or there is no diffraction peak. In fact, it indicates that the particles are sufficiently low in crystallinity, amorphous, or in the form of fine particles such as nanoparticles, so that the formation of dendrite can be suppressed. In addition, since the negative electrode contains an electron conductive material, the electron conductivity also becomes good.

FIG. 1 is a partial perspective view schematically showing a configuration of a nickel-based secondary battery according to an embodiment of the present invention. It is a figure which shows typically the lamination | stacking state of the positive / negative electrode of the nickel type secondary battery which concerns on one Embodiment of this invention, and a separator. It is a perspective view which shows typically an example of the positive electrode of the nickel-type secondary battery which concerns on one Embodiment of this invention. It is a diffraction intensity-diffraction angle figure obtained by the X-ray-diffraction method of an example of the positive electrode active material which satisfy | fills conditions (A) of one embodiment of this invention manufactured by a suitable manufacturing method. It is a diffraction intensity-diffraction angle figure obtained by the X-ray-diffraction method of the positive electrode active material manufactured by the conventional manufacturing method.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The matters other than those specifically mentioned in the specification and necessary for the practice of the present invention (for example, the general configuration and manufacturing process of a nickel-based secondary battery which do not characterize the present invention) This can be understood as a design matter of a person skilled in the art based on prior art in the field. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show the same effect | action. In addition, dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect actual dimensional relationships.

  In the present specification, the term "secondary battery" refers to a storage device in general that can be repeatedly charged and discharged, and is a term including storage devices such as so-called storage batteries and electric double layer capacitors. In addition, "nickel-based secondary battery" refers to any secondary battery using nickel hydroxide, nickel oxyhydroxide or a derivative thereof as the positive electrode active material of the positive electrode, a nickel-hydrogen secondary battery, a nickel-iron secondary battery It is a term that includes batteries, nickel zinc secondary batteries, and the like.

  FIG. 1 is a partial perspective view schematically showing a configuration of a nickel-based secondary battery 100 according to the present embodiment. The nickel-based secondary battery 100 includes a case 40 including a lid 42. The nickel-based secondary battery 100 has a positive electrode 10, a negative electrode 20, and a separator 30, which are housed in a case 40. The positive electrode 10 is connected to the positive electrode terminal 14 via the positive electrode current collecting member 12. The negative electrode 20 is also connected to a negative electrode terminal (not shown) via a negative electrode current collector (not shown). A gasket 50 is provided on the case inner side of the lid 42, and a spacer 60 is further provided. The case 40 contains an electrolytic solution (not shown).

  FIG. 2 is a view schematically showing the configuration of the positive electrode 10, the negative electrode 20, and the separator 30 of the nickel-based secondary battery 100 according to the present embodiment. A plurality of positive electrodes 10 and a plurality of negative electrodes 20 are alternately stacked, and a single separator 30 is interposed between the positive electrode 10 and the negative electrode 20 so as to insulate the positive electrode 10 from the negative electrode 20.

  In the nickel-based secondary battery 100 according to the present embodiment, the configuration other than the positive electrode 10 and the negative electrode 20 may be the same as that of the conventional nickel-based secondary battery. For example, for the separator 30, a resin material (eg, sulfonated polypropylene non-woven fabric, etc.) subjected to hydrophilization treatment can be used. An alkaline aqueous solution containing potassium hydroxide or the like can be used as the electrolytic solution.

  The positive electrode 10 and the negative electrode 20 each have a current collector and an active material held by the current collector. The current collector may be similar to that of a conventional nickel-based secondary battery, and a metal member capable of holding an active material can be used, and a porous metal member is suitably used. It is also possible to use a metal member without holes for the current collector.

  As an example of a structure of a positive / negative electrode, an example of the positive electrode 10 of the nickel-type secondary battery 100 which concerns on this embodiment in FIG. 3 is shown typically. In FIG. 3, a punching metal is used as the positive electrode current collector 16, and the punching metal is wound in a flat shape so that the positive electrode 10 is substantially flat. The positive electrode active material 18 is filled in the pores of the positive electrode current collector 16. The positive electrode active material 18 is also held on the surface of the positive electrode current collector 16. As a modification, there may be a positive electrode in which the hole of the punching metal is closed by the solid electrolyte and the positive electrode active material is held on the surface of the positive electrode current collector.

  The configuration of the negative electrode 20 may be similar to that of FIG. That is, a punching metal is used for the negative electrode current collector, and the punching metal is wound in a flat shape so that the negative electrode 20 is substantially flat. The negative electrode active material is filled in the pores of the negative electrode current collector. The negative electrode active material is also held on the surface of the negative electrode current collector. As a modification, there may be a negative electrode in which the hole of the punching metal is closed by a solid electrolyte and the negative electrode active material is held on the surface of the negative electrode current collector.

The nickel-based secondary battery 100 according to this embodiment satisfies one or both of the following conditions (A) and (B).
(A) The positive electrode 10 includes a positive electrode active material containing at least one selected from nickel hydroxide, nickel oxyhydroxide, and derivatives thereof, and an electron conductive material dispersed in the positive electrode active material, In the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using CuKα ray when the substance is in the state containing nickel hydroxide, the diffraction peak intensity corresponding to the crystal 001 plane of nickel hydroxide The half width is 2 (2θ °) or more, or there is no diffraction peak.
(B) The negative electrode 20 includes a negative electrode active material containing at least one selected from iron hydroxide, iron oxyhydroxide, zinc oxide, and derivatives thereof, and an electron conductive material dispersed in the negative electrode active material. In a diffraction intensity-diffraction angle diagram obtained by powder X-ray diffraction using CuKα radiation when the negative electrode active material contains iron hydroxide or zinc oxide, crystals of iron hydroxide or zinc oxide The half value width of the diffraction peak intensity corresponding to the 001 plane is 2 (2θ °) or more, or there is no diffraction peak.

  First, the condition (A) will be described. The positive electrode active material contained in the positive electrode 10 contains at least one selected from nickel hydroxide, nickel oxyhydroxide, and derivatives thereof which cause an oxidation-reduction reaction during battery operation (hereinafter, nickel hydroxide, oxyhydroxide) Nickel or derivatives thereof may be referred to as "nickel compounds". Although these nickel compounds may have any valence of 2 or more of nickel atoms contained in the compounds, since they cause an oxidation-reduction reaction during battery operation, the average of nickel atoms in the electrode operating potential range is The valence changes. Since the electrode to which these active materials are applied is the positive electrode, reactions such as the equations (3) and (4) described above occur in charge and discharge, but the species of these reaction equations are simplified to the last In fact, it may take various forms which differ in the valence number and hydration number of nickel. In addition, with nickel hydroxide and derivatives of nickel oxyhydroxide, part of nickel elements of nickel hydroxide and nickel oxyhydroxide is another metal element (eg, cobalt, aluminum, zinc, manganese, tungsten, titanium, niobium, etc. , Ruthenium, gold and the like). It is preferable that the substitution rate by other metal elements is 20% or less.

  The nickel compound can be in the state of nickel hydroxide in the discharged state as shown in the formula (4) when it is used in the positive electrode. In addition, since nickel hydroxide is thermodynamically the most stable state in the atmosphere, it is mainly produced in the form of nickel hydroxide when producing an active material. That is, the positive electrode active material can be in a state of containing nickel hydroxide in any process.

The positive electrode active material is a diffraction intensity-diffraction angle diagram obtained by powder X-ray diffraction method using CuKα ray when it is in a state containing nickel hydroxide, a diffraction corresponding to the crystal 001 plane of nickel hydroxide The half width of the peak intensity is 2 (2θ °) or more, or there is no diffraction peak.
The diffraction intensity-diffraction angle diagram is generally obtained as a result of powder X-ray diffraction, and shows the relationship between the diffraction angle 2θ ° and the count number of X-rays. When the substance is crystalline, the regular stacking of crystal planes causes the diffraction phenomenon of X-rays, the count number of X-rays becomes extremely high at a specific diffraction angle corresponding to the plane spacing of crystal planes, and the diffraction intensity A sharp peak is obtained at the diffraction angle position in the diffraction angle diagram. If the order of stacking of crystal planes is broken, or if the particles are small and the number of stacking layers of crystal planes is not large, the peak has a low height and a broad broad band, so the half width (diffraction peak The peak width at half the height of the apex is represented by the angular unit 2θ ° of 2θ). Further, in the case of fine particles such as nanoparticles which are completely amorphous or small enough that a substance can not form crystals, no diffraction peak appears at all at the diffraction angle at which the peak should originally occur when the substance is a crystal. That is, the half width becomes infinite. Therefore, the half-width can be regarded as a scale that indicates the degree of low crystallinity, amorphous, or fine particles such as nanoparticles of the substance, and the larger the value, the lower the crystallinity and the more amorphous or more fine particles. It shows.
Therefore, the fact that the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of nickel hydroxide is 2 (2θ °) or more, or that there is no diffraction peak is nickel hydroxide, nickel oxyhydroxide, which is a positive electrode active material. Alternatively, it indicates that their derivatives are in the state of particles with sufficiently low crystallinity, amorphous or nanoparticles. Thus, the memory effect can be suppressed, and a flat charge / discharge potential curve can be obtained. In the condition (A) of the present embodiment, it is more preferable that the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of nickel hydroxide is 4 (2θ °) or more or there is no diffraction peak.

  The nickel compound may be fine particles having an average particle size of 0.01 to 10 nm, and may be fine particles having an average particle size of 0.5 to 5 nm. In addition, an average particle diameter can be calculated | required as an average value of the diameter of 20 or more particle | grains randomly selected by photographing the fine particle of the said nickel compound with an electron microscope.

  In the condition (A) of the present embodiment, the above-mentioned nickel compound preferably coexists with a metal oxide or a derivative thereof which does not cause a redox reaction during battery operation. The above-mentioned nickel compound is inhibited from aggregation, growth or crystallization of the fine particles by coexistence with other metal oxides or derivatives thereof in the form of fine particles such as nanoparticles, so that it is low in crystallinity, amorphous or like nanoparticles. It is easy to form a state of fine particles, and the fine particles can be stably maintained. In the condition (A) of the present embodiment, since the active material is mainly used in a battery using an alkaline electrolyte, high alkali resistance is also required for the metal oxide coexisting with the above nickel compound or its derivative. . In addition, it is also necessary to have high alkali resistance without causing a redox reaction within the electrode operating potential. Therefore, a zirconate compound is suitable as the metal oxide or its derivative.

The zirconate compound is a compound having ZrO ₂ as a basic unit and containing H ₂ O, which can be represented by the general formula ZrO ₂ · x H ₂ O, but in the condition (A) of the present embodiment The zirconic acid compound refers to zirconic acid and its derivatives, or compounds based on zirconic acid in general. Therefore, some other elements may be substituted as long as the properties of zirconic acid are not impaired, and deviations from the stoichiometric composition or addition of additives is acceptable. For example, salts and hydroxides of zirconic acid also have ZrO ₂ as a basic unit, and derivatives based on salts and hydroxides, or compounds mainly composed thereof are also applicable to the condition (A) of the present embodiment. Included in zirconate compounds.

  In the condition (A) of the present embodiment, a nickel compound may be allowed to coexist with an inorganic / organic hybrid compound in which a metal oxide or a derivative thereof that does not cause a redox reaction during battery operation and an organic polymer having a hydroxyl group are combined. it can. From the point of inhibiting aggregation, growth or crystallization of the fine particles of the nickel compound, the substance coexisting with the above nickel compound can have an amorphous continuum and has the property of being able to contact the whole fine particle of the nickel compound. It is more advantageous and organic polymers are inherently more advantageous than inorganic materials such as metal oxides. However, many organic polymers have low affinity with inorganic substances and tend to be separated, resulting in a reduction in the effect on nickel compounds. Some organic polymers have high affinity to inorganic substances, but many have polar groups and are highly hydrophilic, so they dissolve in the electrolyte. Assuming that an organic polymer having high affinity to an inorganic substance chemically bonds to a nickel compound, elution to the electrolytic solution is suppressed, but the nickel compound causing the redox reaction causes a large change in material during battery operation, so once Even if a chemical bond is formed, it may be dissolved. Moreover, in the battery electrode, active species such as radicals are easily formed, and the positive electrode is also a very strong oxidizing environment. Among organic polymers, hydrocarbon polymers are particularly vulnerable to oxidation and radicals, and It can not withstand the environment and often causes problems such as disassembly. Although the fluorine-based polymer has higher chemical stability, the material itself is expensive, and toxic gas such as hydrogen fluoride is generated at the time of combustion, resulting in cost in waste treatment or recycling treatment. In addition, many organic polymers are hydrophobic, and in that case, they do not absorb the electrolytic solution, and thus block the ion conduction between the nickel compound and the electrolytic solution.

  By using an inorganic / organic hybrid compound as a substance coexisting with the nickel compound, the problems of the organic polymer as described above can be solved. The inorganic / organic hybrid compound to be made to coexist with the nickel compound is a compound in which a metal boride or a derivative thereof which does not cause an oxidation-reduction reaction during battery operation and an organic polymer having a hydroxyl group are chemically bonded. By using an inorganic / organic hybrid compound, an amorphous continuous body can be obtained like an organic polymer, and the entire particle of the nickel compound can be contacted. In addition, since the inorganic / organic hybrid compound also has the property of an inorganic substance, it has a high affinity for the nickel compound and a stable bond, so it is highly effective in inhibiting particle growth, crystal growth and the like. Moreover, as a property of the inorganic substance, resistance to oxidation or radicals is high. Furthermore, even if the organic polymer is hydrophilic, it does not dissolve in the electrolyte because it is compounded with the inorganic substance. Further, the inorganic / organic hybrid compound can absorb the electrolytic solution, and does not inhibit the movement of ions even if the nickel or nickel compound is encased as a continuous body. The degree of dispersibility and ion migration can also be controlled by controlling the hydrophilicity / hydrophobicity of the organic polymer with a block copolymer.

  If the metal oxide of the inorganic / organic hybrid compound or the derivative thereof causes the redox reaction during the operation of the battery, the inorganic / organic hybrid compound also largely changes while the battery is being charged and discharged. . Therefore, it is difficult to keep the inorganic compound in a stable state, such as decomposition of the inorganic / organic hybrid compound itself, which causes a problem in the effect of suppressing fine particle growth and crystallization growth on the nickel compound.

  Therefore, under the condition (A) of the present embodiment, an inorganic / organic hybrid compound in which a metal oxide or a derivative thereof that does not cause an oxidation-reduction reaction during battery operation and an organic polymer having a hydroxyl group is used. In addition, since the active material is mainly used in a battery using an alkaline electrolyte, it is required to have alkali resistance enough to withstand strong alkali. From this point of view, metal oxides of inorganic / organic hybrid compounds or derivatives thereof Also, high alkali resistance is required. From the viewpoint of having high alkali resistance without causing a redox reaction within the electrode working potential, the above-mentioned zirconate compound is preferable as the metal oxide or its derivative.

  Basically, any organic polymer component having a hydroxyl group of the inorganic / organic hybrid compound to be made to coexist with the nickel compound may be used. For example, polyvinyl alcohol and various cellulose derivatives can be used, but the most representative organic polymer is polyvinyl alcohol, and polyvinyl alcohol is bonded to an inorganic substance through its hydroxyl group. When the organic polymer component of the inorganic / organic hybrid compound is polyvinyl alcohol, this polyvinyl alcohol does not have to be a perfect homopolymer, and any polyvinyl alcohol that essentially functions as a polyvinyl alcohol can be used. For example, those in which a part of hydroxyl groups is substituted with another group, and those in which another monomer is copolymerized in part (for example, ethylene-vinyl alcohol polymer) can also function as polyvinyl alcohol . In particular, as described above, a block copolymer may be used to control hydrophilicity and hydrophobicity. The organic polymer may have an electron conductive structure such as a pyrrolidone structure or a thiophene structure introduced or may be crosslinked.

  In the inorganic / organic hybrid compound, a metal oxide or a derivative thereof that does not cause a redox reaction during battery operation and an organic polymer having a hydroxyl group are chemically bonded. That is, both are entangled with each other at the molecular level or at the Nalbel, and are strongly linked by dehydration condensation via the hydroxyl group of the organic polymer. The inorganic / organic hybrid compound is a compound and is distinguished from a mixture of a metal oxide or a derivative thereof and an organic polymer by physical mixing. That is, unlike mixtures, in inorganic / organic hybrid compounds, the chemical properties of each component are not necessarily retained after hybridization. For example, polyvinyl alcohol, which is a component of the organic / inorganic hybrid compound, is independently water soluble (hot water soluble), but is basically not soluble in hot water after forming a hybrid compound with the zirconate compound. Because of the change in chemical properties after hybridization, it can be said that these are hybrid compounds different from physically mixed mixtures.

  In the inorganic / organic hybrid compound, when the amount of the inorganic substance to the organic polymer is too small, sufficient water resistance, alkali resistance and oxidation resistance can not be obtained. On the other hand, when the amount of the inorganic substance is too large, the flexibility is impaired and the function of wrapping the nickel compound fine particles is impaired. Therefore, it is preferable to control so that the weight ratio of the metal oxide or the derivative thereof to the organic polymer which does not cause the redox reaction in the hybrid compound is 0.01 to 1.

  Alternatively, the inorganic / organic hybrid compound may be formed of a nickel compound and an organic polymer having a hydroxyl group. In the inorganic / organic hybrid compound, the nickel compound and the organic polymer having a hydroxyl group are chemically bonded. That is, both are entangled with each other at the molecular level and at the Nalbel, and they are strongly linked by dehydration condensation via the hydroxyl group of the organic polymer.

  In the positive electrode 10, an electron conductive material is dispersed in the positive electrode active material. Thereby, the electron conductivity of the positive electrode can be improved. The electron conductive material is preferably one containing nickel, gold, ruthenium or carbon as a main component. As an electron conductive material containing carbon as a main component, fibrous materials such as carbon fibers and carbon nanotubes (in particular, those having an aspect ratio (length / diameter) exceeding 100) are preferable. Although cobalt compounds (CoOOH) generally used at present can be applied, they are not recommended because they may elute from the electrode during high temperature operation or positive electrode low potential and cause internal short circuit due to adhesion to the separator etc. .

  The shape of the electron conductive material is not particularly limited. It may be spherical or fibrous. For example, the spherical electron conductive material may be dispersed by adhering to the surface of the nickel compound, or the fibrous electron conductive material may be dispersed in the nickel compound fine particles.

  The amount of the electron conductive material mixed is not limited, but is preferably 25% by weight or less, more preferably 0.01% by weight to 10% by weight, based on the positive electrode active material. If the mixing amount is too small, the effect of improving the electron conductivity can not be expected, and if it is added too much, it is not preferable because it leads to concern about internal short circuit and increase in electrode thickness.

  Next, the suitable manufacturing method of the positive electrode active material used for the positive electrode 10 is demonstrated. The positive electrode active material can be obtained by neutralizing the salt of a metal component of a metal oxide or a derivative thereof which does not cause a redox reaction with a nickel salt with an alkali in the presence of an organic polymer having a hydroxyl group. According to such a method, a positive electrode active material in which fine particles of a nickel compound are dispersed in the aforementioned inorganic / organic hybrid compound can be obtained.

  As an organic polymer which has a hydroxyl group used here, what was mentioned as an organic polymer which has a hydroxyl group of the inorganic / organic hybrid compound mentioned above can be used. In addition, an organic polymer converted to polyvinyl alcohol under an alkali such as polyvinyl acetate can also be used as a starting material because it is converted to an organic polymer having a hydroxyl group (polyvinyl alcohol) in the above reaction process.

  The nickel salt is usually in a stable state in which nickel is in a divalent state, and neutralization with an alkali produces nickel hydroxide in an environment that is not particularly oxidizing or reducing. However, in the method, since an organic polymer having a hydroxyl group coexists, nickel hydroxide is also bonded to the organic polymer through the hydroxyl group upon formation. That is, small nickel hydroxides that have been neutralized and formed are unstable and try to be stabilized in connection with something. At this time, if there is only a nickel salt, the newly formed nickel hydroxides combine, aggregate and grow, but if there is an organic polymer having a hydroxyl group in the vicinity, it also combines with the organic polymer. Because nickel hydroxide combines with the organic polymer, the growth of nickel hydroxide is suppressed, and nickel hydroxide remains as fine particles such as nanoparticles. In this way, fine particles such as nickel hydroxide nanoparticles can be produced in this way. Thus, nickel hydroxide bound to the organic polymer at the molecular level, navel, also inhibits crystallization.

  The nickel salt is preferably a water-soluble salt, and nickel sulfate, nickel nitrate, nickel chloride, nickel acetate, or a hydrate thereof or the like can be used, and the water content and the like may be arbitrary. The metal oxide or derivative thereof which does not cause a reduction reaction during battery operation is preferably a zirconate compound, but as its salt, a zirconate compound is formed by neutralization with an alkali, and a zirconate compound As long as it produces a stable inorganic / organic hybrid compound of and an organic polymer having a hydroxyl group, any one may be used. For example, zirconium salts and oxyzirconium salts can be used, and zirconium oxychloride, zirconium acetate, zirconium nitrate or their hydrates can also be used.

  The method forms a solid by removing a solvent from a solution in which a nickel salt, a salt of a metal component of a metal oxide or a derivative thereof which does not cause redox reaction, and an organic polymer having a hydroxyl group coexist. This can be carried out by contacting the solid with an alkali to neutralize the salt of the metal component of the metal oxide or derivative thereof which does not cause a redox reaction with the nickel salt in the solid.

  Specifically, as a raw material, a solvent, a nickel salt, a salt of a metal oxide or a derivative thereof which does not cause a redox reaction during battery operation, and an organic polymer having a hydroxyl group are prepared. Next, these raw materials are mixed to obtain a raw material solution in which a nickel salt, a salt of a metal oxide or a derivative thereof which does not cause a redox reaction during battery operation, and an organic polymer having a hydroxyl group coexist. At this time, any solvent may be used as long as it can dissolve nickel salts, salts of metal oxides or derivatives thereof that do not cause redox reaction during battery operation, and organic polymers having hydroxyl groups. The best solvent is water. In addition, what is necessary is just to dissolve cobalt salt and a zinc salt in a raw material solution, when you want to carry out the solid solution of cobalt and zinc to a positive electrode active material.

  Next, a solvent is removed from a raw material solution in which a nickel salt, a salt of a metal oxide or a derivative thereof that does not cause a redox reaction during battery operation, and an organic polymer having a hydroxyl group are obtained to obtain a solid. The solid may be in any form, and may be in the form of a film, thread, powder or the like. In terms of ease of handling, a membrane is desirable. In order to obtain a film-like solid, the raw material solution may be cast on a flat surface and then the solvent may be removed by heating. In the case of obtaining a thread-like solid, for example, the solvent may be removed by heating at the same time as the raw material solution is ejected from a thin nozzle of the mouth. It is also possible to use an electrospinning method in which an electric field is applied to the raw material solution to fly out in thread form. In the case of obtaining a powdery solid, the solvent may be removed by heating while spraying the raw material solution (spray dry method).

  Thereafter, the solid is brought into contact with an alkali, and a nickel salt and a metal oxide or a derivative thereof salt which does not cause a redox reaction during battery operation are respectively neutralized to obtain a positive electrode active material. In order to efficiently neutralize in a short time, it is desirable that the specific surface area of the solid is large. If it is film-like, the thickness is 1 mm or less, if it is thread-like, the diameter is 1 mm or less, powder However, a size of 1 mm or less in diameter is desirable. Any alkali may be used as long as it can neutralize nickel salts and salts of metal oxides or derivatives thereof that do not cause redox reaction during battery operation, and potassium hydroxide, sodium hydroxide, hydroxide Lithium etc. can be used. These may be used alone or in combination of two or more. When an alkaline solution is used, the concentration of the alkali may be basically any value, but the time for the neutralization step may be shortened, the change in the solution concentration during the neutralization reaction may be suppressed, or It is preferable that the concentration of the alkaline solution is high, from the viewpoint of performing the neutralization reaction before each component of the solution is eluted. As a method of bringing the solid into contact with alkali, there is a method of immersing the solid in an alkali solution, applying or spraying an alkali solution on the solid, or exposing the solid to alkali vapor.

  The nickel hydroxide particles produced in the method are inhibited from growth by the formation of a hybrid compound of a metal oxide or a derivative thereof and an organic polymer which does not cause bonding with an organic polymer or an adjacent redox reaction, and crystallization is also possible. Because it is suppressed, in the diffraction intensity-diffraction angle diagram obtained by powder X-ray diffraction, whether the half value width of the diffraction peak intensity corresponding to the crystal 001 plane is 2 (2θ °) or more or 4 (2θ °) or more There is no diffraction peak. For reference, FIG. 4 shows a diffraction intensity-diffraction angle diagram obtained by the X-ray diffraction method of an example of the positive electrode active material satisfying the condition (A) of the present embodiment manufactured by the manufacturing method described above. In FIG. 5, the diffraction intensity-diffraction angle figure obtained by the X-ray-diffraction method of the positive electrode active material manufactured by the conventional manufacturing method is shown.

  In addition, when it is necessary to avoid the possibility of dissolution in the electrolyte or oxidative decomposition that may occur when the organic polymer in the inorganic / organic hybrid compound is incorporated into a sealed battery, it can be oxidized and removed in advance. . In this case, the method of heating in air is the simplest, and can be oxidized by heating, for example, at 200 to 300 ° C. At this time, if heating at a temperature of 250 ° C or more for a long time, dehydration occurs from nickel hydroxide, which may become nickel oxide and become inactive against charge and discharge. Is good. The residue after the organic polymer oxidation is ideally removed by water washing or alkali washing.

  When it is desired to form an inorganic / organic hybrid compound with a nickel compound and an organic polymer having a hydroxyl group, the above method can be performed without adding a salt of a metal oxide or a derivative thereof which does not cause an oxidation reduction reaction during battery operation. You can do

  Next, the condition (B) will be described. The negative electrode active material contained in the negative electrode 20 contains at least one selected from iron hydroxide, iron oxyhydroxide, zinc oxide and derivatives thereof (hereinafter referred to as iron hydroxide, iron oxyhydroxide and derivatives thereof In addition, zinc oxide and its derivatives may be referred to as “zinc compounds.” Also, “iron compounds” and “zinc compounds” may be collectively referred to as “negative electrode metal compounds”. There is Although these iron compounds and zinc compounds may have any valence of 2 or more of the metal atoms contained in the compounds, since they cause an oxidation-reduction reaction during battery operation, metals within the electrode operating potential range The average valence of the atoms changes. Since the electrode to which these active materials are applied is a negative electrode, reactions such as the equations (5) to (8) described above occur during charge and discharge, but in these reaction equations, the species of material that appear to the last are simplified It is shown in the form, and in fact, it may take various forms different in valence, hydration number and so on. In addition, with iron hydroxide and derivatives of iron oxyhydroxide, a part of iron elements of iron hydroxide and iron oxyhydroxide is another metal element (eg, cobalt, tungsten, titanium, niobium, ruthenium, gold, etc.) Refers to compounds substituted with It is preferable that the substitution rate by other metal elements is 20% or less. In addition, the derivative of zinc oxide refers to a compound in which part of the zinc element of zinc oxide is substituted with another metal element (eg, cobalt, tungsten, titanium, niobium, ruthenium, gold, etc.). It is preferable that the substitution rate by other metal elements is 20% or less.

  When used in the negative electrode, the iron compound can be in the state of iron hydroxide in a discharged state as shown in the formula (6). In addition, when the zinc compound is used in the negative electrode, it can be in the state of zinc oxide in a discharged state as shown in the formula (8).

In the case where the negative electrode active material contains an iron compound, the negative electrode active material contains water, in the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using CuKα rays, The half value width of the diffraction peak intensity corresponding to the crystal 001 plane of iron oxide is 2 (2θ °) or more, or there is no diffraction peak.
As described above, in the diffraction intensity-diffraction angle diagram, the half-width of the peak can be regarded as a scale indicating the degree of low crystallinity, amorphous or fine particles such as nanoparticles of the substance, and the larger the value, the more crystalline. Is low, indicating that it is more amorphous or more finely divided.
Therefore, the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of the iron hydroxide is 2 (2θ °) or more, or that there is no diffraction peak, the iron compound or zinc compound which is the negative electrode active material is sufficiently In the form of low crystallinity, amorphous or in the form of fine particles such as nanoparticles.
And thereby, the formation of the passive state can be suppressed. In the condition (B) of the present embodiment, it is more preferable that the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of iron hydroxide is 4 (2θ °) or more or there is no diffraction peak.

In the case where the negative electrode active material contains a zinc compound, the negative electrode active material contains zinc oxide, in the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using a CuKα ray, The half value width of the diffraction peak intensity corresponding to the crystal 001 plane of 2 or more is 2 (2θ °) or more, or there is no diffraction peak.
As described above, in the diffraction intensity-diffraction angle diagram, the half-width of the peak can be regarded as a scale indicating the degree of low crystallinity, amorphous or fine particles such as nanoparticles of the substance, and the larger the value, the more crystalline. Is low, indicating that it is more amorphous or more finely divided.
Therefore, if the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of zinc oxide is 2 (2θ °) or more or there is no diffraction peak, the iron compound or zinc compound which is the negative electrode active material is sufficiently It represents that it is in the state of fine particles such as low crystallinity, amorphous or nanoparticles.
And thereby, generation of dendrite can be suppressed. In the condition (B) of the present embodiment, it is more preferable that the half value width of the diffraction peak intensity corresponding to the crystal 001 plane of zinc oxide is 4 (2θ °) or more or there is no diffraction peak.

  The negative electrode metal compound may be fine particles having an average particle size of 0.01 to 10 nm, and may be fine particles having an average particle size of 0.5 to 5 nm. In addition, an average particle diameter can be calculated | required as an average value of the diameter of 20 or more particle | grains randomly selected by photographing the fine particle of the said negative electrode metal compound with an electron microscope.

  In the condition (B) of the present embodiment, the negative electrode metal compound preferably coexists with a metal oxide or a derivative thereof that does not cause a redox reaction during battery operation. The aforementioned iron compound and zinc compound are inhibited from aggregation, growth or crystallization of fine particles by coexistence with other metal oxides or their derivatives in the state of fine particles such as nanoparticles, and low crystallinity, amorphous or nano It becomes easy to form the state of particulates like particles, and the particulates can be stably maintained. The coexisting metal oxide or the derivative thereof is the same as the coexisting metal oxide or the derivative thereof in the condition (A), and a zirconate compound is preferable.

  In the condition (B) of the present embodiment, like the nickel compound of the condition (A) of the present embodiment, the negative electrode metal compound is a metal oxide or a derivative thereof that does not cause a redox reaction during battery operation and a hydroxyl group. It can also be made to coexist with the inorganic / organic hybrid compound which compounded with the organic polymer which it has. The contents of the inorganic / organic hybrid compound are the same as described above. The action of the inorganic / organic hybrid compound is also the same as described above, and coexistence of the inorganic / organic hybrid compound can inhibit aggregation / growth or crystallization of fine particles of the negative electrode metal compound.

  Alternatively, an inorganic / organic hybrid compound may be formed by the negative electrode metal compound and the organic polymer having a hydroxyl group. In the inorganic / organic hybrid compound, the negative electrode metal compound and the organic polymer having a hydroxyl group are chemically bonded. That is, both are entangled with each other at the molecular level and at the Nalbel, and they are strongly linked by dehydration condensation via the hydroxyl group of the organic polymer.

  In the negative electrode 20, an electron conductive material is dispersed in the negative electrode active material. Thereby, the electron conductivity of the negative electrode can be improved. The electron conductive material is preferably one containing nickel, gold, ruthenium or carbon as a main component. As an electron conductive material containing carbon as a main component, fibrous materials such as carbon fibers and carbon nanotubes (in particular, those having an aspect ratio (length / diameter) exceeding 100) are preferable. Although cobalt compounds (CoOOH) generally used at present can be applied, they are not recommended because they may elute from the electrode at high temperature operation or at a low potential of the negative electrode and cause internal short circuit by adhesion to a separator or the like.

  The amount of the electron conductive material mixed is not limited, but is preferably 25% by weight or less, more preferably 0.01% by weight to 10% by weight, based on the negative electrode active material. If the mixing amount is too small, the effect of improving the electron conductivity can not be expected, and if it is added too much, it is not preferable because it leads to concern about internal short circuit and increase in electrode thickness.

Next, the suitable manufacturing method of the negative electrode active material used for the negative electrode 20 is demonstrated. The negative electrode active material can be produced in the same manner as the method for producing a positive electrode active material used under the condition (A) of the present embodiment described above. For example, when the negative electrode 20 is an iron electrode, a negative electrode active material can be produced by using an iron salt instead of a nickel salt. That is, it can be obtained by neutralization with an alkali in the presence of an organic polymer having a hydroxyl group and a salt of a metal component of a metal oxide or a derivative thereof which does not cause an oxidation reduction reaction with an iron salt. The iron salt may be of any type as long as it dissolves in the solvent used, and iron sulfate, iron nitrate, iron chloride, iron acetate or their hydrates may be used, and the water content etc. May be anything.
When the negative electrode is a zinc electrode, a negative electrode active material can be produced by using a zinc salt instead of a nickel salt. That is, it can be obtained by neutralizing a zinc salt and a metal component of a metal component of a metal oxide or a derivative thereof which does not cause a redox reaction with an alkali in the coexistence of an organic polymer having a hydroxyl group. According to such a method, a negative electrode active material in which fine particles of a negative electrode metal compound are dispersed in the above-mentioned inorganic / organic hybrid compound can be obtained. The zinc salt may be of any type as long as it dissolves in the solvent used, and zinc sulfate, zinc nitrate, zinc chloride, zinc acetate or their hydrates may be used, and the water content etc. May be anything.

  When it is desired to form an inorganic / organic hybrid compound by using a negative electrode metal compound and an organic polymer having a hydroxyl group, the above-described method can be performed without adding a salt of a metal oxide or a derivative thereof which does not cause an oxidation reduction reaction during battery operation. You just have to do it.

  The nickel-based secondary battery 100 according to the present embodiment satisfies one or both of the conditions (A) and (B) described above for the electrode. When the nickel-based secondary battery 100 according to the present embodiment satisfies only the condition (A), the negative electrode 20 may have the same configuration as the negative electrode of the conventional nickel-based secondary battery. When the nickel-based secondary battery 100 according to the present embodiment satisfies only the condition (B), the positive electrode 10 may have the same configuration as that of the conventional nickel-based secondary battery. It is preferable that the nickel-based secondary battery 100 according to the present embodiment satisfy both the conditions (A) and (B) described above.

  Next, a method of manufacturing the nickel-based secondary battery 100 according to the present embodiment will be described. First, an electrode is produced. Since the positive electrode 10 of the condition (A) and the negative electrode 20 of the condition (B) can be manufactured through the same process by replacing the material to be used such as the active material, the manufacturing method and conditions of the positive electrode 10 of the condition (A) Hereinafter, a method of manufacturing the negative electrode 20 of (B) will be collectively described as a method of manufacturing an electrode.

  First, an electrode slurry containing an electrode active material and an electron conductive material is prepared. The electrode slurry can be produced by physically mixing an electrode active material, an electron conducting material, and a solvent. When such an electrode slurry is used, the electron conductive material can be dispersed in the fine particles of the electrode active material. Alternatively, the electrode slurry is prepared by preparing a slurry containing an electrode active material and a solvent, and depositing an electron conductive material on the fine particle surface of the electrode active material by a deposition method such as PVD, CVD, PECVD, atmospheric pressure PECVD. An electrode slurry is prepared. When such an electrode slurry is used, the electron conductive material adheres to the surface of the fine particles of the electrode active material, whereby the electron conductive material can be dispersed in the electrode active material. The electrode active material may be one that is hybridized with a polymer having a hydroxyl group. In addition, the above-mentioned inorganic / organic hybrid compound may be mixed in the electrode slurry.

  The electrode slurry is applied to a current collector. The current collector can be a known one, for example, a punched metal, a plain weave, or a combination of these can be used. Hereinafter, the case where a punching metal is used for the current collector will be described as an example.

  As the punching metal, nickel foil is preferably used when the electrode is a positive electrode, and nickel plated steel foil is preferably used when the electrode is a negative electrode. The thickness of the punching metal is preferably 10 μm or less. The aperture ratio of the punching metal may be appropriately set from the balance with the strength, preferably 50% or more, and more preferably 70 to 95%. The punched metal may have irregularities periodically. The height of the asperities may be such that electron conduction can be made between the layers of the punching metal to be wound. The periodicity of the asperities may be either in the TD direction or in the MD direction, but it is preferable from the viewpoint of production that it is parallel to the MD direction.

  An electrolyte coating solution containing a solid electrolyte is applied to the current collector, dried, and the holes of the punching metal are sealed. The solid electrolyte may be an anion-permeable or cation-permeable material, and particularly preferably a polymer material such as polyvinyl alcohol or ethylene-vinyl alcohol copolymer. The solid electrolyte may contain a layer separation structure in the molecule in order to improve ion permeability. The electrolyte coating solution is preferably applied so that the thickness after drying is 5 μm or less. Subsequently, the electrode slurry is applied to a current collector and dried to dispose an electrode active material on the current collector. The electrode slurry is preferably applied so that the thickness after drying is 5 μm or less (in particular, 1 μm or less). The electrode slurry may be applied to only one side of the current collector, or may be applied to both sides. The application of the electrolyte coating solution and the electrode slurry is continuously performed while feeding the current collector from the current collector roll. However, application may be performed batchwise on the current collector sheet. The coating method is not particularly limited, and a cast method, a screen printing method, a T-die, a method using a lip coater, etc. can be applied. The electrode active material may be formed as a film having a uniform thickness, or may be formed as a film having irregularities. In addition, it may be applied on the current collector in an island shape. In addition, when an electrode slurry can form a self-supporting film | membrane by containing an inorganic / organic hybrid compound, application | coating of a solid electrolyte can be skipped. In this case, the electrode active material seals the hole of the punching metal and is disposed on the surface of the punching metal.

  The electrode can be manufactured by winding the current collector to which the electrode active material is applied. At this time, the current collector may be wound around the core electrode. As a core electrode, when producing a positive electrode, a nickel plate etc. can be used when producing a negative electrode, such as a nickel plate. When winding the current collector on the core electrode, it is preferable to electrically and physically bond the core electrode and the current collector by ultrasonic welding or the like. The current collector is continuously fed from the current collector roll, but the current collector may be slit as appropriate. There is no particular limitation on the number of winding times. The winding direction is not particularly limited, and may be parallel or perpendicular to the coating direction. The winding is preferably performed so that the holes of the punching metal are positioned in different phases. After winding, a physical press may be applied in the normal direction. After winding, the current collector may be magnetized to be magnetized in order to provide a binding force between the wound current collectors. An electrolyte may be coated on the outermost surface to suppress dendrite generation from the outermost layer. In addition, when the current collector has unevenness, a gap may be generated between the wound current collectors. In this case, the gap may be filled with the electrode slurry. The preparation of the electrode is preferably performed under a reducing atmosphere (for example, under an atmosphere containing hydrogen) in order to suppress side reactions.

  As another manufacturing method of the electrode, after the electrode slurry is applied to the current collector and dried using the electrode slurry not containing the electron conductive material, the electron conductive material is mixed in the electrode active material by the above evaporation method. May be Moreover, after apply | coating and drying an electrode slurry to a collector, the method of producing | generating an electron conduction material in an electrode active material electrochemically is also possible.

  In addition, when the electrode active material coexists with the organic / inorganic hybrid compound, or when the electrode active material is an organic / inorganic hybrid compound, an electron conductive material (preferably, after forming a fibrous sheet by electrospinning) The electrode may be manufactured by vapor deposition of nickel) and winding while laminating a plurality of fibrous sheets. According to such a method, the metal structure can be introduced into the fibrous sheet containing the electrode active material, and the organic / inorganic hybrid compound can be coated with the electron conductive material, but the area coverage of the electron conductive material is 30 to 80% is preferred. The fiber diameter of the fibrous sheet is preferably 10 μm or less. The thickness of the metal structure is preferably 5 μm or less. The plurality of fibrous sheets may have a thickness of 10 to 30 μm at the stage of lamination, preferably have a porosity of 20 to 80%, and then preferably be compressed to remove the voids . Compression may be performed with heating to prevent fracture of the metal structure.

  When the present embodiment satisfies only the condition (A), the negative electrode can be produced according to a known method. When the present embodiment satisfies only the condition (B), the positive electrode can be produced according to a known method.

  The positive electrode and the negative electrode produced as described above are alternately stacked while interposing a separator to produce an electrode body, and a nickel-based secondary battery can be produced according to a known method.

  A positive electrode, a negative electrode, a separator or an electrolyte interposed between positive and negative electrodes, and a back separator may be stacked and wound to produce an electrode body, and a nickel-based secondary battery may be produced according to a known method. It is preferable from the viewpoint of internal resistance reduction and heat dissipation improvement that the back conductive material is coated or adhered to the both surfaces of the back conductive material, which are mutually insulated.

  The nickel-based secondary battery 100 according to the present embodiment can be used for various applications, and suitable applications include vehicles such as electric vehicles (EVs), hybrid vehicles (HVs), plug-in hybrid vehicles (PHVs), etc. The drive power supply mounted is mentioned.

  Although the specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 10 Positive electrode 12 Positive electrode current collection member 14 Positive electrode terminal 20 Negative electrode 30 Separator 40 Case 42 Lid 50 Gasket 60 Spacer 100 Nickel-based secondary battery

Claims (1)

A nickel-based secondary battery comprising a positive electrode, a negative electrode, and an electrolytic solution, wherein one or both of the following conditions (A) and (B) are satisfied:
(A) The positive electrode includes a positive electrode active material containing at least one selected from nickel hydroxide, nickel oxyhydroxide, and derivatives thereof, and an electron conducting material dispersed in the positive electrode active material,
At least one selected from the above-mentioned nickel hydroxide, nickel oxyhydroxide and derivatives thereof is a fine particle having an average particle diameter of 0.01 to 10 nm,
The electron conductive material contains nickel, gold, ruthenium, or carbon as a main component,
In the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using the CuKα ray when the positive electrode active material is in a state containing nickel hydroxide, the diffraction corresponding to the crystal 001 plane of nickel hydroxide The half width of the peak intensity is 2 (2θ °) or more, or there is no diffraction peak corresponding to the crystal 001 plane of nickel hydroxide .
(B) The negative electrode includes a negative electrode active material containing at least one selected from iron hydroxide, iron oxyhydroxide, zinc oxide, and derivatives thereof, and an electron conductive material dispersed in the negative electrode active material,
At least one selected from iron hydroxide, iron oxyhydroxide, zinc oxide, and derivatives thereof is a fine particle having an average particle size of 0.01 to 10 nm,
In the diffraction intensity-diffraction angle diagram obtained by the powder X-ray diffraction method using CuKα radiation when the negative electrode active material contains iron hydroxide or zinc oxide, crystals of iron hydroxide or zinc oxide The half value width of the diffraction peak intensity corresponding to the 001 plane is 2 (2θ °) or more, or there is no diffraction peak corresponding to the crystal 001 plane of iron hydroxide or zinc oxide .

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