JPH08162111A - Active material for nickel electrode and method for producing the same - Google Patents

Abstract

(57) [Summary] [Objective] An active material for a nickel electrode, which suppresses the formation of γ-NiOOH and which has a higher nickel pure content of nickel hydroxide than conventional nickel hydroxide to increase the energy density, and Provide a nickel electrode. [Structure] The active material constituting the alkaline battery is mainly composed of a nickel hydroxide powder active material, 0.1 to 1% by weight of a lanthanoid element or yttrium, and 0.5 to 3% by weight of zinc. Characteristic active material for nickel electrodes.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to alkaline batteries such as nickel-cadmium batteries, and more specifically,
The present invention relates to improvements in nickel electrodes for alkaline batteries and nickel active materials.

[0002]

2. Description of the Related Art In recent years, various electronic devices have been integrated into circuits, and electronic devices have been rapidly reduced in size and weight. Therefore, the portability of the electronic device is improved, and the power supply section for supplying electric power to the electronic device is also becoming cordless. At present, nickel-alkaline batteries using a nickel electrode as a positive electrode are used as a power source for power supply in the cording due to their excellent characteristics. However, along with the reduction in size and weight of electronic devices, the ratio of the battery, which is the power supply unit, to the weight and volume of electronic devices is increasing. Therefore, in order to further reduce the size and weight of electronic devices, increasing the capacity of batteries has become an important issue. Therefore, for the electrodes of nickel-alkaline batteries, nickel electrodes have been used in which various active materials are filled in the concave portions of the nickel-based porous body, dried, and then pressure-molded (see, for example, Japanese Patent Application Laid-Open No. 2000-242242). (Sho 49-127145). However, even with the nickel-alkaline battery manufactured in this manner, the demand for higher capacity in the market has not been sufficiently answered, and a nickel-alkaline battery with a higher capacity is required.

It is said that the deterioration of the life of the nickel electrode constituting the nickel-alkaline battery is mainly due to the swelling of the nickel electrode and the formation of partial protrusions (blisters). Further, the swelling of the nickel electrode is generally considered to be caused by the volume change of the nickel hydroxide active material in the nickel electrode. The nickel hydroxide active material is manufactured in the form of powder so as to be filled in the concave portion of the porous body as described above, for example, as described in JP-A-5-254847. When a nickel-alkaline battery is repeatedly charged and discharged normally, the nickel hydroxide in the nickel electrode is charged from β-Ni (OH) ₂ to β-Ni.
Changes to OOH, and conversely, β-NiOOH due to discharge
Is considered to change from β-Ni (OH) ₂ .

If only the above reaction is repeated,
The volume change of the nickel electrode is unlikely to occur. However, when the nickel-alkaline battery is repeatedly charged and discharged, locally uneven current density may occur inside the nickel electrode, which causes γ-NiOOH which is a higher oxide. Will occur. γ-Ni
When the nickel-alkaline battery discharges, OOH partially changes to β-Ni (OH) ₂ , but most of it changes to very low density α-Ni (OH) ₂ . Therefore, when γ-NiOOH is generated, the nickel electrode has a low density due to repeated charging and discharging, and it cannot be restored. This phenomenon is
The more charging and discharging are repeated, the worse it gets.
As a result, the electrode swells. In order to reduce the swelling of the nickel electrode generated as described above, in advance,
A method is disclosed in which a buffer space capable of absorbing swelling is provided in the nickel electrode to prevent the swelling of the nickel hydroxide active material from directly swelling the nickel electrode. However, in this case, as a result, the packing density of the nickel hydroxide active material is reduced, which, conversely, reduces the capacity of the nickel electrode.

On the other hand, it has been attempted to control the production of γ-NiOOH itself, and it has already been found that the addition of Cd is effective for this. Furthermore, recently, Cd
It has been reported that similar effects can be obtained not only by adding Zn or Mg. (Battery Handbook, Maruzen Co., Ltd., published on August 20, 1990, p. 233) Since the crystal lattice of nickel hydroxide is distorted by these additional elements, H ⁺ which is involved in the reaction in nickel hydroxide It is said that the mobility in the nickel hydroxide lattice is improved and the production of γ-NiOOH is suppressed. In order for Zn to exert such a swelling suppressing effect, as described in Japanese Patent Publication No. 2-30061, 3% by weight or more (3 to 10% by weight) of zinc is solid in the nickel hydroxide crystal. Must be in solution. However, the swelling suppressing element such as Zn only suppresses the swelling of the electrode and is not directly involved in the battery reaction. Therefore, when such a swelling-suppressing element is added, the addition amount thereof is relatively large, so that the nickel grade directly involved in the battery reaction in nickel hydroxide is lowered and the capacity of the nickel electrode is lowered. In other words, the closer the nickel grade of the nickel hydroxide active material is to the theoretical grade of 63.3% by weight, the more the capacity of the nickel electrode becomes
Although it will increase, it does not approach the theoretical quality due to the addition of the swelling suppressing element. That is, if the swelling of the nickel electrode can be suppressed, the smaller the amount of the swelling suppressing element such as Zn added, the better. The addition of zinc and yttrium to nickel hydroxide is disclosed in JP-A-5-28992, but nickel hydroxide contains zinc and yttrium in an amount of 1 to 7%, and the capacity and swelling of the nickel electrode. Suppression is not associated.

[0006]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention
It suppresses the production of γ-NiOOH, which is said to be a cause of hindering the life of the nickel electrode used in alkaline batteries, and has a higher nickel grade than the conventional nickel hydroxide active material to increase energy density. It is an object of the present invention to provide an active material for a nickel electrode having a high temperature, a method for producing the same, and a nickel electrode using the same.

[0007]

According to the present invention, nickel
The active material of the nickel electrode constituting the alkaline battery is nickel hydroxide as the main component, zinc, and 0.1 to 1% by weight.
Of the lanthanoid element and / or yttrium and / or scandium. 0.5% by weight of zinc
It is preferably at least 3% by weight. In this case, it is preferable that zinc, a lanthanoid element, yttrium, and scandium are simultaneously added to nickel hydroxide by stirring granulation and the total amount is less than 3% by weight. Further, it is desirable that these elements be in a solid solution state in the nickel hydroxide crystal. The average particle size of the nickel electrode active material is 5 to 10
It is preferably 0 μm.

The nickel electrode of the present invention comprises nickel hydroxide and zinc in the concave portion of the porous alkali metal substrate.
The nickel electrode active material is filled with 0.1 to 1% by weight of a lanthanoid element and / or yttrium and / or scandium. Zinc is 0.
It is preferably 5% by weight or more and less than 3% by weight. It is preferable that zinc and a lanthanoid element, yttrium, or scandium are added at the same time, the total amount is less than 3% by weight, and they are in a solid solution state in the nickel hydroxide crystal. In this case, as the porous alkali-resistant metal substrate, a sponge-like nickel porous body obtained by nickel-plating a resin sponge, roasting this, and refining it is preferable.

[0009]

In the present invention, the nickel electrode active material used in the nickel electrode constituting the nickel-alkaline battery is
It is a nickel hydroxide active material containing nickel hydroxide as a main component, and zinc and 0.1 to 1% by weight of a lanthanoid element, yttrium, and scandium added at the same time to stirring granulation and the like. Zinc is preferably 0.5 to 3% by weight, and the total amount of zinc, lanthanoid element, yttrium, and scandium is preferably less than 3% by weight. Zinc, the lanthanoid element, yttrium, and scandium contained in the nickel hydroxide crystal give strain to the nickel hydroxide crystal. In particular, by adding the lanthanoid element and yttrium together with zinc as compared with the case of adding only zinc, crystal distortion is further given, and the same swelling suppressing effect can be obtained with a lower amount of added element. For this reason, it is desirable that these elements are granulated by stirring and are in a solid solution state.

Further, the lanthanoid element and yttrium are usually trivalent, and when they are replaced with the nickel element in the nickel hydroxide crystal, they function as donors and emit electrons to improve the conductivity of the nickel hydroxide active material. Can also be considered. Due to such an effect, the freedom of action of protons and electrons in the crystal is increased, and as a result, the production of γ-NiOOH is suppressed, and the same amount of additional elements is used as in the conventional nickel electrode containing only zinc. A swelling suppression effect can be obtained. In the case of a nickel hydroxide active material to which only zinc is added, it is necessary to add 3% by weight or more to suppress swelling, and the nickel quality in the nickel hydroxide active material is 5%.
It is 7 to 58% by weight. However, in the present invention, since the swelling suppressing effect is exhibited even with 0.5% by weight of zinc and 0.5% by weight of the lanthanoid element or yttrium, the nickel grade in the nickel hydroxide active material is 60 to 62% by weight. %, The nickel grade is increased by 3 to 5% by weight as compared with the conventional one in which only zinc is added. The increase in nickel quality in the nickel hydroxide active material means that the amount of electrochemical reaction increases in the nickel hydroxide active material per unit weight.

By using the nickel electrode active material of the present invention, it is possible to extract 4 to 6% more electricity per unit weight than the conventional nickel hydroxide active material. To increase the capacity of the battery. In the case of the present invention, the amount of the lanthanoid element, yttrium, and scandium added to the nickel hydroxide active material is 0.05 to 1% by weight, and the addition concentration of zinc is 0.5 to 3% by weight. Is preferred. This is because when the lanthanoid element or yttrium added to the nickel hydroxide active material is 0.1% by weight or less, the effect of suppressing the swelling of the nickel electrode is not sufficiently exerted, and in order to suppress the swelling, It is desirable that 0.5% by weight or more of zinc be present, and conversely, if the amount of zinc added exceeds 3% by weight, the swelling suppression effect does not improve at all, and the nickel grade in the nickel hydroxide active material is only zinc. Since it becomes the same as the conventional one added with, and the superiority cannot be exhibited, if the addition amount of the lanthanoid element, yttrium, or scandium exceeds 1% by weight, deviation of the lanthanide element, yttrium, or scandium occurs, and water This is because the density of the nickel oxide active material particles is reduced and the electric capacity of the nickel electrode is reduced.

When the lanthanoid element, yttrium, scandium, and zinc are in a solid solution state in the nickel hydroxide crystal, it is possible to avoid a decrease in the density of the nickel hydroxide particles due to their deviation and to effectively distort the crystal. Can be generated. Further, the nickel electrode active material is in the form of particles having an average particle diameter of 5 to 100 μm, and thus more preferable results are presented. Average particle size is 5μ
When it is smaller than m or larger than 100 μm, the filling property into the concave portion of the porous substrate supporting the active material is deteriorated. That is, it is smaller than the concave portion of the porous substrate and drops, or larger than the concave portion and cannot be filled. Further, in the present invention, 0.1 to 1% by weight of the lanthanoid element, yttrium, scandium, and zinc are contained in the concave portion of the porous alkali-resistant metal substrate with nickel hydroxide as a main component in a total amount of 3%.
Since the nickel electrode filled with the active material for the nickel electrode added in less than wt% is provided, the electric capacity of the battery can be increased.

In the case of the present invention, the porous alkali-resistant metal plate is a sponge-like nickel porous body obtained by subjecting a resin sponge to nickel plating, roasting and refining the nickel sponge. Increase the electric capacity. Further, in the present invention, the average space portion diameter of the porous alkali metal substrate forming the nickel electrode is 100 μm to 100 μm.
The capacity of the nickel battery can be further increased by filling the space (recess) with particles of the nickel hydroxide active material together with the powder of cobalt or nickel and setting the thickness to 0 μm. However, the reason has not been clarified. In the present invention,
The lanthanoid element added to the nickel hydroxide active material means an element included in the lanthanoid series that starts with lanthanum and ends with ruthenium in the periodic table of the elements. When the lanthanoid element, yttrium, and scandium are added at the same time as zinc to the nickel hydroxide active material, good results are shown even if one or more of these elements coexist. Be done.

[0014]

EXAMPLES Examples of the present invention will be described in detail below. (Example 1) An aqueous solution prepared by adding lanthanum nitrate and zinc sulfate to a nickel sulfate solution was prepared, and aqueous ammonia was added dropwise to this solution to form an ammine complex ion of nickel. By vigorously stirring the solution dropwise, the complex ions were decomposed, and the nickel hydroxide particles in which zinc and lanthanum were made into a solid solution were gradually extruded. The above-mentioned nickel hydroxide particles in which zinc and lanthanum are solidified are washed with water to remove anions and sodium ions adhering to the surface thereof, and then the amount of zinc added is 2 using a stirring granulator. Nickel hydroxide particles having an average particle diameter of 5 μm, in which the amount of lanthanum added was 0.5% by weight and the Ni quality was 60.2%, were granulated. The tap density of the nickel hydroxide particles was 2.0 g / ml.

On the other hand, a porous alkali-resistant metal substrate is coated with nickel on a resin sponge, which is roasted,
It was formed of a sponge-like nickel porous body obtained by refining. 50 parts by weight of the nickel hydroxide particles and 45 parts by weight of nickel powder were placed in the recesses of the sponge-like nickel porous body.
A nickel electrode was prepared by filling 5 parts by weight of cobalt powder and a paste containing carpoxymethyl cellulose as a thickener, drying and compressing. Then, the above nickel electrode is used as a positive electrode, a negative electrode is provided with a cadmium electrode having an excess capacity as compared with the positive electrode, and a glass bipolar electrode cell partitioned by a glass filter is used to obtain a concentration of 30% by weight. An open model cell was assembled using an aqueous solution of potassium hydroxide as an electrolytic solution.

After charging the above model cell with a current equivalent to 0.1 C for 12 hours, 0.5
It was discharged to 1.0 V with a current equivalent to C. After that, charge the battery with a current equivalent to 1C for 5 hours, and with a current equivalent to 1C, 1.0
Discharged to V. After discharging, the thickness of the electrode is measured, and the swelling amount of the electrode is calculated by comparing with the thickness of the electrode before charging, and the discharge capacity is measured, and the discharge and the theoretical electric capacity of nickel hydroxide used in this case The utilization rate as a nickel electrode active material was calculated. Hereinafter, the expansion coefficient presented as a series of measurement values is represented by a value (× 100) obtained by dividing the thickness of the electrode after charging by the thickness of the electrode before charging. The swelling ratio of the nickel electrode measured in Example 1 is 10
It was 3%, and the utilization rate of the nickel electrode active material was 8
It was calculated to be 6%.

(Example 2) The amount of zinc added is 1.0% by weight.
Then, an open type model cell was assembled in the same manner as in Example 1 except that nickel hydroxide particles (average particle diameter 12 μm) having a Ni grade of 61.0% were used, and charging and discharging were performed in the same manner as in Example 1. As a result of repeating the measurement, the tap density of the nickel hydroxide particles was 2.01 g / ml, the utilization rate of the active material was 86%, and the swelling rate of the nickel electrode was 105%.

(Example 3) The amount of zinc added is 0.5% by weight.
Then, an open type model cell was assembled in the same manner as in Example 1 except that nickel hydroxide having an Ni grade of 61.0% (average particle size 20 μm) was used, and charging and discharging were performed in the same manner as in Example 1. As a result of repeated measurement, the tap density of nickel hydroxide was 2.01 g / ml, the utilization rate of the active material was 84%, and the swelling rate of the electrode was 110%.

Example 4 Example 4 was repeated except that nickel hydroxide (average particle size: 8 μm) containing 0.1% by weight of lanthanum and having Ni quality of 60.1% was used. As a result of assembling an open model cell and repeating charging and discharging in the same manner as in Example 1, the tap density of nickel hydroxide was 2.00 g / ml, the active material utilization rate was 86%, and the electrode The swelling rate was 112%.

(Example 5) The amount of lanthanum added was 0.1% by weight, the amount of zinc added was 0.5% by weight, and the Ni grade was 6%.
An open model cell was assembled in the same manner as in Example 1 except that 1.5% nickel hydroxide (average particle size: 9 μm) was used, and measurement results were obtained by repeating charging and discharging as in Example 1. , Nickel hydroxide has a tap density of 2.0
It was 5 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 120%.

(Example 6) Nickel hydroxide (average particle size 7) in which 0.5% by weight of cerium was added instead of lanthanum
The open type model cell was assembled in the same manner as in Example 1 except that (1 μm) was used, and measurement was performed while repeating charging and discharging in the same manner as in Example 1, and as a result, the tap density of nickel hydroxide was 2.00 g / ml, the active material utilization rate is 8
6%, the swelling ratio of the electrode was 104%.

Example 7 In place of lanthanum, 0.5% by weight of praseodymium was added, and the Ni quality was 60.1.
% Nickel hydroxide (average particle size 11 μm) was used, an open-type model cell was assembled in the same manner as in Example 1, and measurement was performed while repeating charging and discharging as in Example 1, and Nickel tap density is 2.00g
/ Ml, the utilization rate of the active material was 86%, and the swelling rate of the electrode was 105%.

Example 8 In place of lanthanum, 0.5% by weight of praseodymium was added so that the amount of zinc added was 2.5% by weight, and nickel hydroxide having a Ni grade of 60.1% (average particle size: 10 μm). ) Was used, an open model cell was assembled in the same manner as in Example 1, and measurement was performed while repeating charging and discharging in the same manner as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml. The utilization rate of the active material was 86%, and the swelling rate of the electrode was 105%.

Example 9 Example 1 was repeated except that 0.5% by weight of neodymium was added in place of lanthanum and nickel hydroxide having a Ni quality of 60.1% (average particle size 8 μm) was used. Similarly, as a result of assembling an open model cell and repeating charging and discharging in the same manner as in Example 1, the tap density of nickel hydroxide was 2.00 g / ml, and the utilization rate of the active material was 84%. , The swelling ratio of the electrode is 104
%Met.

(Example 10) 0.5 instead of lanthanum
An open-system model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 7 μm) added with wt% ytterbium was used, and measurement was performed while repeating charging and discharging as in Example 1. As a result, the tap density of nickel hydroxide was 2.00 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 106%.

(Example 11) 0.5 instead of lanthanum
Addition of wt% yttrium, Ni quality is 60.3%
Nickel hydroxide (average particle size: 11 μm) was used, an open-type model cell was assembled in the same manner as in Example 1, and measurement was performed while repeating charging and discharging in the same manner as in Example 1. Has a tap density of 1.98 g /
The utilization rate of the active material was 87%, and the swelling rate of the electrode was 104%.

(Example 12) 0.1 instead of lanthanum
An open-type model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 13 μm) having a Ni grade of 60.8% was used by adding neodymium in an amount of wt%. Similarly, as a result of measurement while repeating charging and discharging, the tap density of nickel hydroxide was 2.06 g /
The utilization rate of the active material was 84%, and the swelling rate of the electrode was 114%.

(Example 13) The amount of lanthanum added was 0.7.
An open type model cell was assembled in the same manner as in Example 1 except that nickel hydroxide (average particle size: 7 μm) having a Ni quality of 60.1% in weight% was used, and charging was performed in the same manner as in Example 1. As a result of measurement while repeating discharge, the tap density of nickel hydroxide was 2.01 g / ml, the utilization rate of the active material was 83%, and the swelling rate of the electrode was 104%.

(Comparative Example 1) The same procedure as in Example 1 was performed except that the amount of lanthanum added was 1.1% by weight and nickel hydroxide having an Ni quality of 58.7% (average particle size 6 μm) was used. As a result of assembling an open model cell and repeating charging and discharging in the same manner as in Example 1, the nickel hydroxide tap density was 1.85 g / ml, the active material utilization rate was 75%, and the electrode The swelling ratio was 104%.

Comparative Example 2 The amount of lanthanum added was 0.08.
In the same manner as in Example 1 except that nickel hydroxide (average particle size: 9 μm) having a Ni quality of 60.5% was used as a weight%, an open model cell was assembled and charged as in Example 1. As a result of measurement while repeating discharge, the tap density of nickel hydroxide was 2.05 g / ml, the utilization rate of the active material was 84%, and the swelling rate of the electrode was 128%.

COMPARATIVE EXAMPLE 3 No lanthanoid element or yttrium was added, only 2.0% by weight of zinc was added,
Nickel hydroxide with Ni grade of 60.3% (average particle size 11
The open type model cell was assembled in the same manner as in Example 1 except that (1 μm) was used, and measurement was performed while repeating charging and discharging in the same manner as in Example 1, and as a result, the tap density of nickel hydroxide was 2.08 g / ml, the active material utilization rate is 8
6%, the swelling ratio of the electrode was 130%.

(Comparative Example 4) Without adding the lanthanoid element or yttrium, only 3.1% by weight of zinc was added,
Nickel hydroxide with Ni grade of 57.9% (average particle size 6μ
The open type model cell was assembled in the same manner as in Example 1 except that m) was used, and measurement was performed while repeating charging and discharging in the same manner as in Example 1, and as a result, the tap density of nickel hydroxide was 2.03 g / ml, the active material utilization rate is 86
%, The swelling ratio of the electrode was 110%.

The results of the above Examples and Comparative Examples are shown in Table 1.

[0034]

[Table 1] Zn La, etc. Ni tap density Swelling utilization rate Average particle size (wt%) (g / ml) (%) (%) (μm) Example 1 2.0 La 0.5 60.2 2.00 103 586 5 2 1.0 La 0.5 61.0 2.01 105 105 86 12 3 0.5 La 0.5 61.0 2.01 110 84 20 4 2.0 La 0.1 60.1 2.00 112 86 8 5 0.5 La 0.1 61.5 2.05 120 83 83 9 6 2.0 Ce 0.5 60.2 2.00 104 86 7 7 2.0 Pr 0.5 60.1 2.00 105 86 86 11 8 2.5 La 0.5 60.0 2.04 103 86 6 9 2.0 Nd 0.5 60.1 2.00 104 84 8 8 10 2.0 Ib 0.5 60.2 2.00 106 83 7 7 11 2.0 Y 0.5 60.3 1.98 104 87 11 12 12 2.0 Nd 0.1 60.8 2.06 114 84 13 13 2.0 La 0.7 60.1 2.01 104 837 Comparative Example 1 2.0 La 1.1 58.7 1.85 104 75 6 2 2.0 La0.08 60.5 2. 05 128 84 9 3 2.0-60.3 2.08 130 86 11 4 3.1-57.9 2.03 110 86 6

[0035]

The active material for a nickel electrode and the nickel electrode according to the present invention are constituted as described above.
It is possible to suppress the generation of —NiOOH, and to improve the nickel grade as compared with the conventional nickel hydroxide active material to enhance the energy density.

Claims (9)

[Claims] 1. A nickel hydroxide active material constituting a nickel electrode of an alkaline battery comprises 0.1 to 1% by weight of a lanthanoid element, zinc, and substantially the balance nickel hydroxide, and a lanthanoid element. The total amount of zinc is 3% by weight
An active material for a nickel electrode, which is less than 2. The nickel hydroxide active material constituting the nickel electrode of an alkaline battery comprises 0.1 to 1% by weight of a lanthanoid element and / or yttrium and / or scandium, and 0.5% by weight or more and less than 3% by weight. Of zinc and the balance of nickel hydroxide, and the total amount of the lanthanoid element, yttrium, and scandium is 3
An active material for a nickel electrode, characterized by being less than wt%. 3. The active material for a nickel electrode according to claim 1, wherein nickel hydroxide is agitated and granulated together with the lanthanoid element and / or yttrium and / or scandium and zinc. 4. The lanthanoid element is La, Ce, Pr,
One or more types of Nd and Yb, The active material for nickel electrodes in any one of Claims 1-2 characterized by the above-mentioned. 5. The nickel hydroxide active material has an average particle size of 5 μm.
Particles having a size of m to 100 μm.
The active material for a nickel electrode according to any one of 1 to 3. 6. A concave portion of a porous alkali metal resistant substrate,
A nickel electrode, wherein the nickel electrode active material according to any one of claims 1 to 4 is filled together with nickel powder and cobalt powder. 7. The nickel electrode according to claim 5, wherein the porous alkali-resistant metal substrate is a sponge-like nickel porous body obtained by subjecting a resin sponge to nickel plating, roasting and baking. 8. The concave portion of the porous alkali metal resistant substrate,
The nickel electrode according to claim 5, which has an average diameter of 100 μm to 1000 μm. 9. A lanthanoid element and / or yttrium and zinc are solid-dissolved in nickel hydroxide, and 0.1 to 1% by weight of the lanthanoid element and / or yttrium and 0.5 to 3% by weight. A method for producing an active material for a nickel electrode, the method comprising forming a particulate nickel hydroxide active material containing zinc and.