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(19) 



Europaisches Patentamt 
European Patent Office 
Office europeen des brevets 



(12) 



(id EP 0 793 285 A1 

EUROPEAN PATENT APPLICATION 



(43) Date of publication: 

03.09.1997 Bulletin 1997/36 

(21) Application number: 97301225.5 

(22) Date of filing: 25.02.1997 



(51) intci.*: H01M 4/52, C01G 53/04 



(84) Designated Contracting States: 


• Okada, Yukihiro 


DE FR GB 


Katano City, 576 (JP) 




• Ohta, Kazuhiro 


(30) Priority: 29.02.1996 JP 43294/96 


Sanda City, 669-13 (JP) 




• Toyoguchi, Yoshinorl 


(71) Applicant: MATSUSHITA ELECTRIC INDUSTRIAL 


Yao City, 581 (JP) 


CO., LTD. 




Kadoma-shi, Osaka-fu, 571 (JP) 


(74) Representative: Thomas, Roger Tamlyn et al 




D. Young & Co. 


(72) Inventors: 


21 New Fetter Lane 


• Matouda, Hlromu 


London EC4A 1DA(GB) 


Hyogo Pref., 666-02 (JP) 





(54) Active material and positive electrode for alkaline storage battery 



(57) The present invention provides a high perform- 
ance composite hydroxide active material which facili- 
tates charging at high temperatures. It comprises a solid 
solution nickel hydroxide material having additive ele- 



ments incorporated therein. The additive elements com- 
prise at least one element selected from Fe, Cr, V, Ti, Y, 
La, Ce, Al, and Pb, and at least one element selected 
from Mn and Co. 



CO 
CM 

CO 

o 

CL 
UJ 



Prin1»d by Jouva, 75001 PARIS (FR) 



EP 0 793 285 A1 



Description 

The present invention relates to a nickel hydroxide active material and a positive electrode using the same for 
alkaline storage batteries. 

s Conventionally, composite hydroxides prepared from nickel hydroxide dissolving one or more elements such as 

Co, Al, Mn, Fe, Cr, etc. in solid solution have been focused on to realize a nickel hydroxide active material having a 
high capacity (C. Delmas, et al.: Materials Science and Engineering, B13, 89-96 (1992) and L Indira, et al.: Journal 
of Power Sources, 52, 93-97 (1994). 

In these methods, part of element Ni included in the nickel hydroxide active material is substituted with Co, Al, Mn, 
10 Fe, Cr, or the like, thereby to cause an exchange of more than one electron in the oxidation-reduction reaction of the 
nickel hydroxide, rather than only one electron that is normal in an alkaline solution. 
The prior art technologies have the following drawbacks: 

Oxidation-reduction equilibrium potential of the composite hydroxide active material is likely to vary depending on 
the species of elements to be substituted for element Ni. This means that charge and discharge potentials vary at the 
is same time. Selection of an element which lowers charge potential in order to increase charge efficiency at high tem- 
peratures adversely leads to a reduction in discharge potential at the same time. As a result, available discharge energy 
decreases. 

Another drawback is that selection of an element which elevates discharge potential in order to increase discharge 
energy leads to an elevation of charge potential at the same time. This causes a small difference between the charge 

20 potential and oxygen evolution potential, and the charge efficiency at high temperatures decreases. 

The present invention provides an active material for an alkaline storage battery comprising a solid solution nickel 
hydroxide materia! having additive elements incorporated therein, the additive elements comprising at least one ele- 
ment selected from group A consisting of Fe, Cr, V, Ti, Y, La, Ce, Al, and Pb, and at least one element selected from 
group B consisting of Mn and Co. 

2S The positive electrode for an alkaline storage battery in accordance with the present invention comprises the 

above-mentioned active material and a compound of at least one element selected from the group consisting of Y, Ba, 
Ca, Sr, Cd, Cu, and Ag. 

While the novel features of the invention are set forth particularly in the appended claims, the invention, both as 
to organization and content, will be better understood and appreciated, along with other objects and features thereof, 
30 from the following detailed description. 

The present invention is based on the following finding: 

When at least one element selected from group A consisting of Fe, Cr, V, Ti, Y, La, Ce, Al, and Pb, all of which 
have a tendency in a solid solution nickel hydroxide material to elevate or maintain the oxidation-reduction equilibrium 
potential of the nickel hydroxide, and at least one element selected from group B consisting of Mn and Co, which have 
35 a tendency to lower the oxidation-reduction equilibrium potential of the nickel hydroxide, are contained together in the 
solid solution nickel hydroxide material, a minimal decrease in discharge potential can be secured even when the 
charge potential is decreased greatly. 

The present invention can realize a high performance composite hydroxide active material with less impaired 
discharge characteristic which facilitates charging at high temperatures with exceptional efficiency. 
40 Particularly, a high technical effect can be obtained when each of group A element and group B element occupies 

3 mol % or more of the total amount of element Ni, group A element and group B element, and the sum of the contents 
of group A element and group B element is 50 mol % or less. 

Preferably, the sum of the contents of group A element and group B element occupies not less than 10 mol % and 
not more than 30 mol % of the total amount of element Ni, group A element and group B element. 
45 The nickel hydroxide active material of the present invention can be obtained by a commonly known method of 

producing a nickel hydroxide powder or a nickel hydroxide electrode plate. More specifically, it can be produced by 
one of the methods including precipitation, oxide hydrolysis, metal hydroxylation, electrodeposition, various impreg- 
nation processes, and the like, which facilitate preparation of a composite solid solution material having additive ele- 
ments in the solid solution. The active material is obtained as a granulated powder, a thin film, or an electrode plate 
so impregnated with the active material. 

The synthesis by precipitation is a representative method of producing a powder. In this method, an aqueous 
solution dissolving a nickel salt and salts of additive elements is successively supplied into a reaction chamber, together 
with an alkaline aqueous solution so as to cause nuclear generation and crystalline growth at the same time. This 
method can give a highly porous spherical composite hydroxide powder. A complex forming agent such as ammonia 
55 and the like may be further added at the same time for stabilization of crystalline growth, if necessary. 

The above-mentioned additive elements are at least one element selected from the aforementioned group A and 
at least one element selected from the aforementioned group B. A sulfate or a nitrate is usually used as the salt. 
The electrodeposition is a representative method of forming a thin film. By cathodic polarizing an electrode sub- 



2 



EP 0 793 285 A1 



strate in an aqueous solution of nickel nitrate and nitrates of the additive elements, a composite hydroxide thin film can 
be formed on the electrode substrate. 

The present invention can realize a nickel hydroxide positive electrode with good charge efficiency at higher tem- 
peratures, since the positive electrode comprises not solely the aforementioned solid solution nickel hydroxide material 
s having group A element and group B element in the solid solution, but also a compound of at least one element selected 
from the group consisting of Y, Ba, Ca, Sr, Cd, Cu, and Ag, all of which are known to elevate the oxygen evolution 
potential. 

The positive electrode for alkaline storage batteries in accordance with the present invention can be prepared by 
a representative process of filling a mixture of the solid solution nickel hydroxide material having group A element and 
10 group B element incorporated therein, which was prepared by the above-mentioned precipitation, and a compound of 
Y or the like, into a substrate, such as a foamed metal substrate, a metallic fiber substrate, and the like. 

Preferable examples of the compound of Y or the like may be exemplified as Y 2 (C0 3 ) 3 , Y 2 0 3 , BaO, Ca(OH) 2 , 
CaO, CaF 2 , CaS, CaS0 4 , CaSi 2 0 5 , CaC 2 0 4 , CaW0 4 , SrC0 3 , Sr(OH) 2 , CdO, Cu 2 0, Ag 2 0, and the like. 

It is preferable to contain these compounds not less than 0. 1 wt% in order to elevate the oxygen-evolution potential, 
15 and not more than 5 wt% because addition of these compounds in larger amounts adversely decreases the capacity 
of the positive electrode. 

The active material and the positive electrode for alkaline storage batteries in accordance with the present invention 
can be applied to alkaline storage batteries having an electrolyte of an alkaline aqueous solution, such as nickel- 
cadmium storage batteries, nickel-metal hydride storage batteries including a hydrogen storage alloy negative elec- 
20 trode, nickel-iron storage batteries, nickel-zinc storage batteries, etc. 

In the following, the present invention will be described by way of examples. 

Example 1 

25 A mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Fe(N0 3 ) 3 , 

and 100 cc of an aqueous solution of 0.1 M Co(N0 3 ) 2 was poured in an electrolysis vessel. A 0.15-mm-thick platinum 
substrate for electrolytic deposition (one surface has an area of 10 cm 2 ) and a 0. 15-mm-thick nickel substrate serving 
as a counter electrode (one surface has an area of 100 cm 2 ) were immersed in the mixture. Then, the platinum substrate 
was polarized cathodically for electrolysis for 5 sec at a current of 10 mA/cm 2 per surface at room temperature. After 

30 electrolysis, the platinum substrate was removed from the vessel, washed with water, and dried at room temperature. 
The resultant platinum substrate was used as the electrode of Example 1. 

Example 2 

35 An electrode for Example 2 was prepared in the same manner as applied for Example 1 , except for the use of a 

mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Cr(N0 3 ) 3 , and 100 
cc of an aqueous solution of 0.1 M Co(N0 3 ) 2 . 

Example 3 

40 

An electrode for Example 3 was prepared in the same manner as applied for Example 1 , except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni(NO a ) 2 , 100 cc of an aqueous solution of 0. 1 M V(N0 3 ) 3 , and 100 
cc of an aqueous solution of 0.1 M Co(N0 3 ) 2 . 

45 Example 4 

An electrode for Example 4 was prepared in the same manner as applied for Example 1 , except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Ti(S0 4 ) 2 , and 100 
cc of an aqueous solution of 0.1 M Co(N0 3 ) 2 . 

50 

Example 5 

An electrode for Example 5 was prepared in the same manner as applied for Example 1, except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni{N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M La(N0 3 ) 3 , and 
55 100 cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 



3 



EP 0 793 285 A1 



Example 6 

An electrode for Example 6 was prepared in the same manner as applied for Example 1, except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Ce(N0 3 ) 3 , and 
5 100 cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Example 7 

An electrode for Example 7 was prepared in the same manner as applied for Example 1 , except for the use of a 
io mixture of 800 cc of an aqueous solution of 0. 1 M Ni(N0 3 ) 2> 1 00 cc of an aqueous solution of 0. 1 M AI(N0 3 ) 3 , and 1 00 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Example 8 

*5 An electrode for Example 8 was prepared in the same manner as applied for Example 1 , except for the use of a 

mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Pb(N0 3 ) 2 , and 
100 cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Comparative Example 1 

20 

An electrode for Comparative Example 1 was prepared in the same manner as applied for Example 1 , except for 
the use of a mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 and 200 cc of an aqueous solution of 0.1 M 
Co(N0 3 ) 2 . 

25 Comparative Example 2 

An electrode for Comparative Example 2 was prepared in the same manner as applied for Example 1 , except for 
the use of a mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 and 200 cc of an aqueous solution of 0.1 M 
Al( N0 3 ) 2 . 

30 

Comparative Example 3 

An electrode for Comparative Example 3 was prepared in the same manner as applied for Example 1 , except for 
the use of a mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Al 
35 (NOg)g, and 100 cc of an aqueous solution of 0.1 M Fe(N0 3 ) 3 . 

Comparative Example 4 

An electrode for Comparative Example 4 was prepared in the same manner as applied for Example 1 , except for 
40 the use of a mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 100 cc of an aqueous solution of 0.1 M Co 
(N0 3 ) 2 , and 100 cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Comparative Example 5 

45 An electrode for Comparative Example 5 was prepared in the same manner as applied for Example 1 , except for 

the use of 1 ,000 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 . 

Half cells were prepared using the thus prepared electrodes of Examples 1 through 8, and Comparative Examples 
1 through 5 as positive electrodes, hydrogen storage alloy negative electrodes having an excess capacity over the 
positive electrodes as counter electrodes, mercury electrodes (Hg/HgO) as reference electrodes, and a 31 wt% aque- 

50 ous solution of KOH as electrolytes. A charge and discharge was performed at a current of 200 uA/cm 2 /surface of 
these electrodes. Charging was started upon complete saturation of the charge potential to a constant value and 
continued for one hour. Discharging was continued up to 0.0 V, with reference to the potential of the reference electrode. 
In these half cells, the discharge capacities (C 10 ) after charging at 10°C and discharging at 20°C in an atmosphere 
and the discharge capacities (C^) after charging at 40°C and discharging at 20°C in an atmosphere were measured, 

55 and a ratio of C 40 to C 10 (C 40 /C 10 ) was determined. Intermediate discharge potentials after charging at 10°C and 
discharging at 20°C were also measured, using the discharge potential of the electrode of Comparative Example 5 as 
reference. The measurement results are summarized in Table 1 below. 



4 



EP 0 793 285 A1 



Table 1 



D/-\r> i t i w £i flloptrivfo 

rOoiuvB eieuirouB 


nicrhornfl ^or^Qoi'ti/ ratio i Oi. \ ( C*" . _ iC^ ^ \ 
UlbUI lal LJU LdpdUILy lallU \ '°) ^^ w/ 4C/^ r lO' 


i nier rnuuiam uiscnaige potential uiiiamnco 
(mV) (compared to Comparative Example 5) 


Example 1 


60 


-20 


Example 2 


85 


-20 


Example 3 


85 


-25 


Example 4 


80 


-20 


Example 5 


75 


-15 


Example 6 


75 


-15 


Example 7 


80 


-10 


Example 8 


75 


-15 


Comparative Example 1 


90 


-90 


Comparative Example 2 


50 


+50 


Comparative Example 3 


45 


+55 


Comparative Example 4 


95 


-85 


Comparative Example 5 


65 


0 



25 The above results indicate that inclusions of at least one element selected from group A consisting of Fe, Cr, V, 

Ti, Y, La, Ce, Al, and Pb in a solid solution nickel hydroxide, which have a tendency to elevate the oxidation-reduction 
equilibrium potential of the nickel hydroxide, and at least one element selected from group B consisting of Mn and Co 
in a solid solution nickel hydroxide, which have a tendency to lower the oxidation-reduction equilibrium potential of the 
nickel hydroxide may facilitate improvement in charge efficiency at high temperatures and prevention of a decrease in 

30 discharge potential at the same time. 

Example 9 

An electrode for Example 9 was prepared in the same manner as applied for Example 1, except for the use of a 
55 mixture of 940 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 30 cc of an aqueous solution of 0.1 M AI(N0 3 ) 3 , and 30 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Example 10 

40 An electrode for Example 1 0 was prepared in the same manner as applied for Example 1 , except for the use of a 

mixture of 900 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 50 cc of an aqueous solution of 0.1 M AI(N0 3 ) 3 , and 50 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Example 11 

45 

An electrode for Example 11 was prepared in the same manner as applied for Example 1 , except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni{N0 3 ) 2 , 150 cc of an aqueous solution of 0.1 M AI(NO g ) g , and 50 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

50 Example 12 

An electrode for Example 12 was prepared in the same manner as applied for Example 1 , except for the use of a 
mixture of 800 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 50 cc of an aqueous solution of 0.1 M AI(N0 3 ) 3 , and 150 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

55 



5 



EP 0 793 285 A1 



Example 13 

An electrode for Example 1 3 was prepared in the same manner as applied for Example 1 , except for the use of a 
mixture of 700 cc of an aqueous solution of 0.1 M Ni(N0 3 ) 2 , 150 cc of an aqueous solution of 0.1 M AI(N0 3 ) 3 , and 150 
5 cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Example 14 

An electrode for Example 14 was prepared in the same manner as applied for Example 1 , except for the use of a 
10 mixture of 500 cc of an aqueous solution of 0. 1 M Ni(N0 3 ) 2 , 250 cc of an aqueous solution of 0. 1 M AI{N0 3 ) 3 , and 250 
cc of an aqueous solution of 0.1 M Mn(N0 3 ) 2 . 

Half cells were prepared by combining each of the electrodes of Examples 9 through 14 as positive electrodes, 
with each of the hydrogen storage alloy electrodes and reference electrodes as stated above. Then, the discharge 
capacity ratio (C 40 /C 10 ) after charging and discharging was measured under the same conditions as applied in the 
is above-mentioned examples, and the intermediate discharge potentials after charging at 1 0°C and discharging at 20°C, 
using the discharge potential of the electrode of Comparative Example 5 as reference. The measurement results are 
listed in Table 2 below. 



Table 2 



Positive electrode 


Discharge capacity ratio (%) (C 40 /C 10 ) 


Intermediate discharge potential difference 
(mV) (compared to Comparative Example 5) 


Example 9 


70 


-10 


Example 1 0 


75 


-10 


Example 11 


70 


-5 


Example 1 2 


85 


-20 


Example 1 3 


80 


-10 


Example 1 4 


70 


-15 


Comparative Example 5 


65 


0 



The above results indicate that a higher effect can be obtained when each of group A element and group B element 
occupies 3 mol % or more of the total amount of element Ni, group A element and group B element, and the sum of 
the contents of group A element and group B element is not less than 5 mol % and not more than 50 mol %. Furthermore, 
it is appreciated that a more preferable range of the sum of the contents of group A element and group B element is 
not less than 10 mol % and not more than 30 mol % of the total amount of element Ni, group A element and group B 
element. 

Example 15 

Aqueous solutions of 1 M NiS0 4 , 1 M AI 2 (S0 4 ) 3 , and 1 M CoS0 4 were mixed in a volume ratio of 8:1:1 (Ni:AI:Cp 
= 80:10:10 in a metallic ion molar ratio). The resultant mixture was successively supplied into a reaction chamber, 
together with an aqueous solution of 2 M sodium hydroxide and a water containing 2 M ammonia, at the same flow 
rate, using a volume-controlled pump, and the mixture was stirred well continuously. Subsequently, a suspension in- 
cluding active material fine particles and other reaction products, which are successively discharged from the reaction 
chamber, was centrifuged to isolate the active material fine particles. The isolated fine particles were washed with an 
alkaline aqueous solution and water and dried at 90° C. The dried particles were used as the active material powder. 
The active material powder (85 g) was mixed and kneaded with cobalt hydroxide (1 5 g) having a mean particle diameter 
of 1.5 u/n and a specific surface area of 25 m 2 /g, while dropping water, and a paste was obtained. The paste was filled 
into a foamed nickel electrode substrate, and dried and pressed. This gave an electrode having a capacity of 1 Ah. 

Example 16 

An active material powder and an electrode for Example 16 were prepared in the same manner as applied for 
Example 15, except for the use of a mixture of aqueous solutions of 1 M NiS0 4 , 1 M AI 2 (S0 4 ) 3 , and 1 M MnS0 4 (Ni: 
AI:Mn = 80:5:15 in a metallic ion molar ratio). 



6 



EP 0 793 285 A1 



Comparative Example 6 

For comparison, an active material powder and an electrode were prepared separately in the same manner as 
applied for Example 15, except for the use of an aqueous solution of 1 M NiS0 4 , instead of the mixture of various 
5 aqueous solutions. 

Similarly, half cells were prepared by combining each of the above-mentioned electrodes of Examples 15 and 16, 
and Comparative Example 6 as positive electrodes, with each of the hydrogen storage alloy electrodes and reference 
electrodes as stated above. Then, the discharge capacity ratio (C 40 /C 10 ) after charging and discharging was measured 
under the same conditions as applied in the above-mentioned examples, and the intermediate discharge potentials 
*0 after charging at 1 0°C and discharging at 20°C, using the discharge potential of the electrode of Comparative Example 
6 as reference. The measurement results are listed in Table 3 below. 



Table 3 



Positive electrode 


Discharge capacity ratio (%) (C 40 /C 10 ) 


Intermediate discharge potential difference 
(mV) (compared to Comparative Example 6) 


Example 15 


80 


-10 


Example 1 6 


75 


-15 


Comparative Example 6 


60 


0 



The above results indicate that the active material powder obtained by the precipitation can have the same technical 
effect as observed with the above-mentioned active material thin film. 



25 Example 17 

An electrode was prepared in the same manner as applied for Example 1 5, using a mixture of the active material 
powder of Example 15 (84 g), CaF 2 (1 g), and the cobalt hydroxide used in Example 15 (15 g). 

30 Example 1 8 

An electrode for Example 18 was prepared in the same manner as applied for Example 17, except for the use of 
Sr(OH) 2 , in place of CaF 2 . 

Similarly, half cells were prepared by combining each of the above-mentioned electrodes of Examples 17 and 18, 
3S and Comparative Example 6 as positive electrodes, with each of the hydrogen storage alloy electrodes and reference 
electrodes as stated above. Then, the discharge capacity ratio (C 40 /C 10 ) after charging and discharging was measured 
under the same conditions as applied in the above-mentioned examples, and the intermediate discharge potentials 
after charging at 10*C and discharging at 20 o C, using the discharge potential of the electrode of Comparative Example 
6 as reference. The measurement results are listed in Table 4 below. 

40 

Table 4 



Positive electrode 


Discharge capacity ratio (%) (C 40 /C 10 ) 


Intermediate discharge potential difference 
(mV) (compared to Comparative Example 6) 


Example 17 


93 


-10 


Example 18 


90 


-10 


Comparative Example 6 


60 


0 



The above results indicate that the composite nickel hydroxide positive electrode including an active material 
comprising the solid solution nickel hydroxide as a main component and further comprising, as additives, element Al 
selected from group A and element Co selected from group B in the solid solution, and a Ca- or Sr- compound has 
exceptional charge efficiency at high temperatures, with less decrease in discharge potential. 

In the above examples, although Al and Co were specifically used as the additive elements incorporated into the 
nickel hydroxide, and a compound of Ca or Sr as a compound mixed with the nickel hydroxide, a substantially similar 
effect may be obtained by a combination of different elements of group A consisting of Fe, Cr, V, Ti, Y, La, Ce, Al, and 
Pb and group B consisting of Mn and Co, and a compound of different elements selected from the group consisting of 
Y, Ba, Ca, Sr, Cd, Cu, and Ag. 



7 



EP 0 793 285 A1 



As discussed above, according to the present invention, it is possible to realize a high performance composite 
hydroxide active material with less impaired discharge characteristic, which facilitates charging at high temperatures 
with exceptional efficiency. 

According to the present invention, it is also possible to realize a composite nickel hydroxide positive electrode 
with less decrease in discharge potential and less impaired discharge characteristic, which facilitates charging at high 
temperature with good efficiency. 

Although the present invention has been described in terms of the presently preferred embodiments, it is to be 
understood that such disclosure is not to be interpreted as limiting, various alterations and modifications will no doubt 
become apparent to those skilled in the art to which the present invention pertains, after having read the above dis- 
closure. Accordingly, it is intended that the appended claims be interpreted as covering all alterations and modifications 
as fall within the true spirit and scope of the invention. 



Claims 

1. An active material for an alkaline storage battery comprising a solid solution nickel hydroxide material having 
additive elements incorporated therein, said additive elements comprising at least one element from (A) Fe, Cr, 
V, Ti, Y, La, Ce, At, and Pb, and at least one element from (B) Mn and Co. 

2. The active material for an alkaline storage battery in accordance with claim 1 , wherein (A) and (B) occupy 3 mol 
% or more of the total amount of Ni, (A) and (B), respectively, and the sum of the contents of (A) and (B) is 50 mol 
% or less. 

3. The active material for an alkaline storage battery in accordance with claim 1 , wherein the sum of the contents of 
(A) and (B) occupies not less than 10 mol % and not more than 30 mol % of the total amount of Ni, (A) and (B). 

4. A positive electrode for an alkaline storage battery having: 

an active material comprising a solid solution nickel hydroxide material containing additive elements incorpo- 
rated therein, said additive elements comprising at least one element from (A) Fe, Cr, V, Ti, Y, La, Ce, Al, and 
Pb, and at least one element from (B) Mn and Co, and 

a compound of at least one element selecled from Y, Ba, Ca, Sr, Cd, Cu, and Ag. 

5. The positive electrode for an alkaline storage battery in accordance with claim 4, wherein said compound of at 
least one element selected from Y, Ba, Ca, Sr, Cd, Cu, and Ag is contained in a range of 0.1 to 5 wt%. 



8 



EP 0 793 285 A1 



Kur„pcan Patent EUROPEAN SEARCH REPORT A " liatim Numb " 

omcc E p 97 30 1225 



DOCUMENTS CONSIDERED TO BE RELEVANT 



Category 



P,X 



P.X 



Citation of document with indication, where appropriate, 
of relevant passages 



EP 0 696 076 A (SANYO ELECTRIC CO) 7 
February 1996 

* claim 1; example 1 * 

WO 96 09657 A (0V0NIC BATTERY CO) 28 March 
1996 

* claims 1,10,11,13,14 * 

EP 0 712 174 A (STARCK H C GMBH CO KG) 15 
May 1996 

* page 3, line 36; claim 1 * 

PATENT ABSTRACTS OF JAPAN 
vol. 095, no. 005, 30 June 1995 
& JP 07 G45281 A (YUASA CORP) , 14 
February 1995, 

* abstract * 

PATENT ABSTRACTS OF JAPAN 

vol. 095, no. 005, 30 June 1995 

& JP 07 037586 A (SHIN KOBE ELECTRIC MACH 

CO LTD), 7 February 1995, 

* abstract * 

PATENT ABSTRACTS OF JAPAN 
vol. 016, no. 488 (E-1277), 9 October 1992 
& JP 04 179056 A (MATSUSHITA ELECTRIC IND 
CO LTD), 25 June 1992, 

* abstract * 



Relevant 

to claim 



1-3 



1-3 



1-3 



1,4 



1,4 



The present search report has been drawn up Tor all claims 



a^SSlKI CATION Or THE 
APPLICATION (lnt.CI.6) 



H01M4/52 
C01G53/04 



TECHNICAL F1E1DS 
SEARCHED (Iot.CI.6) 



H01M 



THE HAGUE 



lilt ut cnpltnu *r tht utrtk 

20 June 1997 



Emriner 

Andrews, M 



CATEGORY OF CITED DOCUMENTS 

X : particularly relmnl If taken alone 

V ; particularly relevant If combined with another 

document of the same category 
A : technological background 
O : doo- written disclosure 
P : tMrnaedUte document 



T : theory or principle underlying the invention 
E : earlier patent document, but published on, or 

after the filing dale 
D : document cited in the application 
L : document dted for other reasons 

A : member of the sane patent family, corresponding 
document 



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