U.S. patent application number 11/387021 was filed with the patent office on 2006-07-20 for preparation of nickel oxyhydroxide.
This patent application is currently assigned to The Gillette Company, a Delaware corporation. Invention is credited to Paul A. Christian, Tatjana Mezini.
Application Number | 20060159993 11/387021 |
Document ID | / |
Family ID | 27803832 |
Filed Date | 2006-07-20 |
United States Patent
Application |
20060159993 |
Kind Code |
A1 |
Christian; Paul A. ; et
al. |
July 20, 2006 |
Preparation of nickel oxyhydroxide
Abstract
Nickel oxyhydroxide can be prepared by exposing a mixture of a
nickel hydroxide and a hydroxide salt to ozone. The nickel
oxyhydroxide is suitable for use in the cathode of a battery.
Inventors: |
Christian; Paul A.; (Norton,
MA) ; Mezini; Tatjana; (Medford, MA) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Assignee: |
The Gillette Company, a Delaware
corporation
|
Family ID: |
27803832 |
Appl. No.: |
11/387021 |
Filed: |
March 21, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10086807 |
Mar 4, 2002 |
|
|
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11387021 |
Mar 21, 2006 |
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Current U.S.
Class: |
429/223 ;
29/623.1; 423/594.19 |
Current CPC
Class: |
H01M 4/52 20130101; C01P
2004/32 20130101; H01M 4/32 20130101; Y10T 29/49108 20150115; C01P
2006/40 20130101; C01P 2002/72 20130101; Y02P 70/50 20151101; C01G
53/04 20130101; Y02E 60/10 20130101; H01M 6/08 20130101; Y10T
29/49115 20150115 |
Class at
Publication: |
429/223 ;
029/623.1; 423/594.19 |
International
Class: |
H01M 4/52 20060101
H01M004/52; H01M 4/04 20060101 H01M004/04; C01G 53/04 20060101
C01G053/04 |
Claims
1-21. (canceled)
22. A battery comprising: a cathode comprising a carbonate-free
nickel oxyhydroxide; an anode; a separator; and an electrolyte.
23. The battery of claim 22, wherein the nickel oxyhydroxide
includes a cobalt oxyhydroxide-modified nickel oxyhydroxide.
24. The battery of claim 22, wherein the nickel oxyhydroxide
includes a cobalt oxyhydroxide-modified gamma-nickel
oxyhydroxide.
25. The battery of claim 22, wherein the anode comprises zinc.
26. The battery of claim 23, wherein the cathode further includes
an oxidizing additive.
27. The battery of claim 26, wherein the oxidizing additive
includes sodium hypochlorite, sodium peroxydisulfate, potassium
peroxydisulfate, potassium permanganate, barium permanganate,
barium ferrate, silver permanganate, disilver oxide, or silver
oxide.
28. The battery of claim 22, wherein the electrolyte includes
potassium hydroxide, sodium hydroxide, lithium hydroxide, or
mixtures thereof.
29-31. (canceled)
Description
TECHNICAL FIELD
[0001] This invention relates to methods of preparing nickel
oxyhydroxide, and devices including nickel oxyhydroxide.
BACKGROUND
[0002] Batteries, such as alkaline batteries, are commonly used as
energy sources. Generally, alkaline batteries have a cathode, an
anode, a separator and an alkaline electrolyte solution. The
cathode can include a cathode material (e.g., manganese dioxide or
nickel oxyhydroxide), carbon particles to enhance the conductivity
of the cathode, and a binder. The anode can be formed of a gel
including zinc particles. The separator is disposed between the
cathode and the anode. The alkaline electrolyte solution, which is
dispersed throughout the battery, can be an aqueous solution of an
alkali metal hydroxide such as potassium hydroxide, sodium
hydroxide, lithium hydroxide or mixtures thereof.
SUMMARY
[0003] An alkaline battery includes a cathode including nickel
oxyhydroxide and an anode including zinc. The nickel oxyhydroxide
can be substantially carbonate-free.
[0004] In one aspect, a method of preparing nickel oxyhydroxide
includes combining a nickel hydroxide and a hydroxide salt in an
inert atmosphere to form a mixture, and exposing the mixture to
ozone to form a nickel oxyhydroxide.
[0005] In another aspect, a primary alkaline battery includes a
cathode, an anode, a separator, and an alkaline electrolyte. The
cathode includes a substantially carbonate-free nickel
oxyhydroxide. The carbonate-free nickel oxyhydroxide is a nickel
oxyhydroxide prepared from a nickel hydroxide in the absence of
carbon dioxide or a carbonate source. The carbonate source can
include lithium carbonate, lithium bicarbonate, sodium carbonate,
sodium bicarbonate, potassium carbonate, or potassium bicarbonate.
The cathode can include an oxidizing additive. The anode can
include metallic zinc or a zinc alloy. The electrolyte can include
potassium hydroxide, sodium hydroxide, lithium hydroxide, or
mixtures thereof.
[0006] In another aspect, a method of manufacturing a battery
includes combining a nickel hydroxide and a hydroxide salt in an
inert atmosphere to form a mixture, exposing the mixture to ozone
to form a nickel oxyhydroxide, and assembling a cathode including
the nickel oxyhydroxide, an anode, a separator, and an electrolyte
to form the battery. The mixture can be a dry mixture.
[0007] In yet another aspect, a method of decreasing capacity loss
during storage for nickel oxyhydroxide batteries includes combining
a cobalt hydroxide-coated nickel hydroxide and a hydroxide salt in
an inert atmosphere to form a mixture, exposing the mixture to
ozone to form a cobalt oxyhydroxide-coated nickel oxyhydroxide,
forming a cathode including the cobalt oxyhydroxide-coated nickel
oxyhydroxide, and assembling the cathode, an anode, a separator,
and an electrolyte to form the battery. The battery can have a
capacity loss after storage for 4 weeks at 60.degree. C. of less
than about 30 percent, as disclosed in co-pending U.S. application
Ser. No. 09/633,067, which is incorporated by reference in its
entirety.
[0008] The inert atmosphere does not react with the nickel
hydroxide. The inert atmosphere can be substantially free of carbon
dioxide, substantially free of water, or substantially free of
both. The inert atmosphere can be argon, nitrogen, helium or
oxygen.
[0009] The nickel hydroxide can include a beta-nickel hydroxide, a
cobalt hydroxide-coated beta-nickel hydroxide, an alpha-nickel
hydroxide, a cobalt hydroxide-coated alpha-nickel hydroxide, a
solid solution of alpha-nickel hydroxide and beta-nickel hydroxide,
or a cobalt hydroxide-coated solid solution of alpha-nickel
hydroxide and beta-nickel hydroxide. The nickel hydroxide can be
substantially dry. The nickel hydroxide can be a powder including
particles having a nominally spherical, spheroidal, or ellipsoidal
shape. The nickel oxyhydroxide can be substantially carbonate-free.
The nickel oxyhydroxide can include a beta-nickel oxyhydroxide, a
cobalt oxyhydroxide-coated beta-nickel oxyhydroxide, a gamma-nickel
oxyhydroxide, a cobalt oxyhydroxide-coated gamma-nickel
oxyhydroxide, a solid solution of a beta-nickel oxyhydroxide and a
gamma-nickel oxyhydroxide, or a cobalt oxyhydroxide-coated solid
solution of a beta-nickel oxyhydroxide and a gamma-nickel
oxyhydroxide.
[0010] The hydroxide salt can include alkali metal hydroxides such
as potassium hydroxide, sodium hydroxide, lithium hydroxide, or
mixtures thereof. The hydroxide salt can be substantially
carbonate-free.
[0011] Typically, the mixture is maintained at a temperature
between 15.degree. C. and 20.degree. C. while exposing the mixture
to ozone. The method can include heating the mixture prior to or
while exposing the mixture to ozone. The mixture can be heated to a
temperature less than about 100.degree. C. In certain
circumstances, the method can include agitating, stirring, mixing
or swirling the mixture while exposing the mixture to ozone.
Exposing the mixture to ozone can include contacting the mixture
with a gas mixture including ozone. The gas mixture can include
dioxygen, water vapor or both. The mixture can be exposed to ozone
for less than 24 hours, less than 12 hours, less than 8 hours, less
than 6 hours, less than 4 hours or less than 3 hours.
[0012] The mixture can include an oxidation-promoting additive,
such as, for example, metallic silver, silver(+1) oxide, silver(+1,
+3) oxide, metallic gold, gold (+3) oxide, gold (+3) hydroxide,
potassium peroxide, potassium superoxide, potassium permanganate,
or silver permanganate. The nickel hydroxide can include at least
one bulk dopant. The bulk dopant can be aluminum, manganese,
cobalt, zinc, gallium, indium, or bismuth. The bulk dopant can be
present at a relative weight percentage of less than about 10%,
less than about 5% or less than about 2%.
[0013] The method of preparing nickel oxyhydroxide can decrease
production times and improve the uniformity of the ozonation
process. The method can eliminate extensive post-production
treatment of the product of the ozonation process, such as, for
example, filtration from a liquid, washing, drying, or separation
from a mixture of products. The method features an improved
synthetic process whereby both the complexity and duration of the
treatment with ozone gas can be decreased substantially relative to
other methods. Carbonate formation attributable to exposing the
finely ground potassium hydroxide powder to moist air, which can
lead to the formation of potassium carbonate, can inhibit
completion of the oxidation process to form fully oxidized
gamma-nickel oxyhydroxide, especially during ozonation of cobalt
hydroxide-coated alpha-nickel hydroxide.
[0014] Other features and advantages of the invention will be
apparent from the description and drawings, and from the
claims.
DESCRIPTION OF DRAWINGS
[0015] FIG. 1 is a drawing depicting a cross section of a
cylindrical alkaline battery.
[0016] FIG. 2 is a graph depicting the x-ray powder diffraction
patterns for: (a) a commercial beta-nickel hydroxide; (b) a mixture
of beta-nickel hydroxide, beta-nickel oxyhydroxide, and a trace
amount of gamma-nickel oxyhydroxide after 2 hours of ozonation; (c)
a mixture of beta-nickel oxyhydroxide and a small amount of
gamma-nickel oxyhydroxide after a total of 4 hours of
ozonation.
[0017] FIG. 3 is a graph depicting the x-ray powder diffraction
patterns for: (a) a cobalt hydroxide-coated, aluminum and cobalt
bulk-doped alpha-nickel hydroxide; (b) a cobalt oxyhydroxide-coated
gamma-nickel oxyhydroxide, after 2 hours of ozonation; (c) a cobalt
oxyhydroxide-coated gamma-nickel oxyhydroxide and trace amounts of
beta-cobalt oxyhydroxide after a total of 8 hours of ozonation.
DETAILED DESCRIPTION
[0018] Nickel oxyhydroxide is prepared by combining a nickel
hydroxide and a hydroxide salt in an inert atmosphere to form a
mixture. The mixture can be a dry mixture. The mixture is exposed
to ozone to form a nickel oxyhydroxide. The ozone can be mixed with
dioxygen to form a treatment gas. The ozone can include sufficient
water vapor to initiate the oxidation process. Excessive amounts of
water vapor in the treatment gas can cause the powder in the
mixture to agglomerate. The mixture can be exposed to ozone, for
example, for less than twenty-four hours, less than twelve hours,
less than six hours or less than four hours, to produce a nickel
oxyhydroxide that contains little or no un-oxidized nickel
hydroxide.
[0019] For example, a mixture of nickel hydroxide and hydroxide
salt can be oxidized via ozonation at a temperature between 5 and
100.degree. C., for example, between 10 and 60.degree. C. or
between 15 and 30.degree. C. to provide a nickel oxyhydroxide. The
temperature of the mixture can be maintained within a 10.degree. C.
range during the ozonation process. The mixture of nickel hydroxide
and hydroxide salt can be formed by manual or mechanical grinding
of a hydroxide salt into a fine powder, followed by manual or
mechanical mixing of the nickel hydroxide with the ground hydroxide
salt, and loading of the resulting mixed powders into a reaction
vessel. The nickel hydroxide, the hydroxide salt, and mixtures
thereof, are handled, ground, and mixed in an inert atmosphere. The
hydroxide salt can include alkali metal hydroxides such as
potassium hydroxide, sodium hydroxide, lithium hydroxide or
mixtures thereof. The hydroxide salt can include silver hydroxide
or gold hydroxide. The hydroxide salt can be in the form of a
free-flowing powder, solid pellets, coarse crystallites, or
agglomerates of crystallites.
[0020] The inert atmosphere is free of carbon dioxide and,
optionally, water. For example, the inert atmosphere can be a dry,
substantially air-free atmosphere. The dry, substantially air-free
atmosphere can be provided inside a glove box purged with an inert
gas stream and protected from infiltration of air. Suitable inert
gases include nitrogen, argon, helium, and oxygen. The grinding and
mixing operations are performed under an inert atmosphere in order
to minimize exposure of the finely divided hydroxide salt to
atmospheric moisture and carbon dioxide since a finely divided
hydroxide salt can react rapidly in the presence of moisture with
atmospheric carbon dioxide to produce a carbonate salt. For
example, potassium hydroxide reacts rapidly with carbon dioxide in
the presence of water vapor to form potassium carbonate. The
presence of a carbonate salt in the mixture can greatly inhibit
completion of oxidation of nickel hydroxide to nickel oxyhydroxide
by ozone. When the nickel hydroxide is substantially carbonate-free
nickel hydroxide, the nickel oxyhydroxide formed is an
carbonate-free nickel oxyhydroxide.
[0021] The mixture can be exposed to ozone in a reaction vessel
suitably modified to minimize infiltration of atmospheric air into
the reaction vessel during the ozonation process. The reaction
vessel can be fabricated from any of a variety of materials that
are resistant to oxidation by ozone gas, such as for example,
glass, fluorinated polymers such as PTFE, Kel-F, PVDF or stainless
steel. The modifications to the reaction vessel can include
attaching a small vestibule having a constricted orifice connected
to the outlet of the reaction vessel to vent the gas flow exiting
from the reaction vessel to the external atmosphere, optionally,
through a gas bubbler. By constricting the orifice, a small
backpressure of ozone gas can be applied to the reaction vessel,
thereby increasing both the partial pressure of ozone and the
average residence time of the ozone gas in the reaction vessel. The
small vestibule also serves to collect any particles ejected from
the reaction vessel or entrained in the exiting gas stream. The
exposure to ozone can be carried out continuously thereby avoiding
the infiltration of air into the reaction vessel before the
ozonation process has been completed.
[0022] The nickel hydroxide can include a beta-nickel hydroxide, a
cobalt hydroxide-coated beta-nickel hydroxide, an alpha-nickel
hydroxide, a cobalt hydroxide-coated alpha-nickel hydroxide, a
solid solution of a beta-nickel oxyhydroxide and gamma-nickel
oxyhydroxide or a cobalt oxyhydroxide coated solid solution of a
beta-nickel oxyhydroxide and gamma-nickel oxyhydroxide. The nickel
hydroxide can be a substantially dry nickel hydroxide powder
including particles having a nominally spherical, spheroidal or
ellipsoidal shape. The average particle size of the nickel
hydroxide powder can be between 1 and 100 microns, 2 and 50 microns
or 5 and 10 microns. Suitable commercial beta-nickel hydroxide
powders including nominally spherical particles can be obtained
from Tanaka Chemical Co. (Fukui, Japan) under the designation type
Z; H.C. Starck GmbH & Co. (Goslar, Germany) under the tradename
Ampergy.RTM. type SNH C15Z40; or OM Group Inc. (Westlake, Ohio). A
suitable cobalt hydroxide-coated beta-nickel hydroxide can be
obtained from Tanaka Chemical Co. (Fukui, Japan) under
the-designation type CoZD; H.C. Starck GmbH & Co. (Goslar,
Germany) under the tradename AMPERGY.RTM. type SNH C15Z40C45; or OM
Group Inc. (Westlake, Ohio).
[0023] Nickel oxyhydroxide can include a beta-nickel(+3)
oxyhydroxide, a cobalt oxyhydroxide-coated beta-nickel(+3)
oxyhydroxide, a gamma-nickel(+3, +4) oxyhydroxide, or a cobalt
oxyhydroxide-coated gamma-nickel(+3,+4) oxyhydroxide.
Gamma-nickel(+3,+4) oxyhydroxide is a non-stoichiometric phase of
nickel oxyhydroxide containing both Ni(+3) and Ni(+4) ions and can
include a variable amount of water molecules, alkali metal cations,
and anionic species inserted into the interlamellar region (viz.,
van der Waals gap) of a layered crystal structure. For example,
Bode et al. proposed a nominal composition of
Na(NiO.sub.2).sub.3.2H.sub.2O for a gamma-nickel oxyhydroxide
prepared by oxidation of NaNiO.sub.2 by bromine in NaOH solution.
See for example, Electrochim. Acta, Vol. 16, 1971, p. 615. Another
related nominal composition proposed for a gamma-nickel
oxyhydroxide is K(NiO.sub.2).sub.3.zH.sub.2O (where z is between
0.5 and 2). See, for example, Corrigan, et al., J. Electrochem.
Soc., Vol. 136, No. 3, 1989, pp. 613-619. Yet another nominal
composition for a gamma-nickel oxyhydroxide is
Ni.sub.0.75[K.sub.Ni].sub.0.25O(OH).sub.1.00, where [K.sub.Ni]
refers to potassium ions located on vacant nickel lattice sites.
See, for example, Cornilsen et al., Proceed. Electrochem. Soc.,
Vol. 86-12, 1986, pp. 114-121. Cobalt oxyhydroxide-coated
gamma-nickel oxyhydroxide can be prepared from a cobalt
hydroxide-coated alpha-nickel hydroxide, such as cobalt
hydroxide-coated, alpha-nickel hydroxide bulk-doped with aluminum,
cobalt or mixtures thereof. Aluminum bulk-doped alpha-nickel
hydroxide can contain up to about.20 atom % of aluminum. Cobalt
bulk doped alpha-nickel hydroxide can contain up to about 10 atom %
of cobalt. A suitable cobalt hydroxide-coated alpha-nickel
hydroxide containing aluminum and cobalt as bulk dopants having a
nominal chemical composition of
Ni.sub.0.62Al.sub.0.18Co.sub.0.06(OH).sub.2(CO.sub.3).sub.0.13.0.17H.sub.-
2O can be obtained from H.C. Starck GmbH &. Co. (Goslar,
Germany) or prepared as disclosed in EP 1,1003,526. The
gamma-nickel oxyhydroxide can include essentially non-fractured
nickel oxyhydroxide particles. The non-fractured gamma-nickel
oxyhydroxide particles can be nominally spherical, spheroidal or
ellipsoidal in shape.
[0024] The cobalt oxyhydroxide coating can improve electrical
contact between particles in the cathode as well as protect the
surface of the nickel oxyhydroxide from degradation by reaction
with the electrolyte. The coating can cover at least 60% of the
surface of the nickel oxyhydroxide. Preferably, the coating can
cover at least 70%, preferably at least 80%, more preferably at
least 90% of the surface. The cobalt oxyhydroxide-modified nickel
oxyhydroxide can be derived from nickel hydroxide coated with
between 2% and 15%, between 3% and 10%, between 4% and 8% or
between 4% and 5% cobalt hydroxide by weight. The cobalt hydroxide
coating can optionally include at least one dopant. The dopant can
be magnesium, calcium, strontium, barium, scandium, yttrium,
lanthanum, rare earth elements, titanium, zirconium, hafnium,
chromium, manganese, nickel, copper, silver, zinc, cadmium,
aluminum, gallium, indium, bismuth or combinations thereof.
[0025] The method can decrease the length of time required to
completely oxidize nickel hydroxide to nickel oxyhydroxide, for
example, beta-nickel hydroxide to beta-nickel oxyhydroxide or
alpha-nickel hydroxide to gamma-nickel oxyhydroxide. In addition,
button cells with cathodes containing gamma-nickel oxyhydroxide
prepared by the method of the present invention can provide both
high-rate and low-rate discharge performance comparable to that
obtained for cells with cathodes containing gamma-nickel
oxyhydroxide prepared from the same cobalt hydroxide-coated
alpha-nickel hydroxide containing aluminum and cobalt as
bulk-dopants subjected to prolonged ozonation after mixing of the
powders in air. For reference, the theoretical one-electron
specific capacity for beta-nickel(+3) oxyhydroxide is about 292
mAhr/g. In the case of the gamma-nickel(+3, +4) oxyhydroxide, the
theoretical specific capacity is about 325 mAhr/g for a 1.1
electron reduction and about 388 mAhr/g for a 1.33 electron
reduction discharge mechanism.
[0026] The oxidation of nickel hydroxide by ozone can be
accelerated by mixing the nickel hydroxide with an
oxidation-promoting additive. The oxidation-promoting additive can
be an additive known to promote oxidation of metal oxides. For
example, a strong oxidant such as a superoxide salt, for example,
potassium superoxide, can be substituted for all or part of the
hydroxide salt mixed with nickel hydroxide -and treated with ozone
gas at room temperature to prepare nickel oxyhydroxide. In another
example, metallic silver, silver oxide, or silver hydroxide can be
mixed with nickel hydroxide and a metal hydroxide and then treated
with ozone. Other oxidation-promoting additives include metallic
gold, gold oxide, or gold hydroxide; potassium permanganate, or
silver permanganate.
[0027] Referring to the FIG. 1, battery 10 includes a cathode 12
(positive electrode), an anode 14 (negative electrode), a separator
16 and a cylindrical housing 18. Battery 10 also includes current
collector 20, seal 22, and a negative metal top cap 24, which
serves as the negatives terminal for the battery. The cathode is in
contact with the housing, and the positive terminal of the battery
is at the opposite end of the battery from the negative terminal.
An electrolytic solution is dispersed throughout battery 10.
Battery 10 can be, for example, an AA, AAA, AAAA, C, or D
cylindrical battery. Alternatively, battery 10 can be a prismatic,
laminar or thin battery or a coin cell or button cell.
[0028] Anode 14 can be formed of any of the standard zinc materials
used in battery anodes. For example, anode 14 can be a zinc slurry
that can include zinc metal particles, a gelling agent, and minor
amounts of additives, such as a gassing inhibitor. In addition, a
portion of the electrolyte solution can be dispersed throughout the
anode.
[0029] The zinc particles can be any of the zinc particles
conventionally used in slurry anodes. Examples of zinc particles
can include those described in U.S. application Ser. No.
08/905,254, U.S. application Ser. No. 09/115,867, or U.S.
application Ser. No. 09/156,915, each of which is hereby
incorporated by reference in its entirety. The anode can include,
for example, between 60 wt % and 80 wt %, between 65 wt % and 75 wt
%, or between 67 wt % and 71 wt % of zinc particles.
[0030] The electrolyte can be an aqueous solution of alkali
hydroxide, such as potassium hydroxide, sodium hydroxide, lithium
hydroxide, or mixtures thereof. The electrolyte can contain between
15 wt % and 60 wt %, between 20 wt % and 55 wt %, or between 30 wt
% and 50 wt % alkali hydroxide dissolved in water. The electrolyte
can contain 0 wt % to 6 wt % of a metal oxide, such as zinc
oxide.
[0031] Examples of a gelling agent can include a polyacrylic acid,
a grafted starch material, a salt of a polyacrylic acid, a
carboxymethylcellulose, a salt of a carboxymethylcellulose (e.g.,
sodium carboxymethylcellulose) or combinations thereof. Examples of
a polyacrylic acid include CARBOPOL 940 and 934 (available from
B.F. Goodrich) and POLYGEL 4P (available from 3V), and an example
of a grafted starch material includes WATERLOCK A221 or A220
(available from Grain Processing Corporation, Muscatine, Iowa). An
example of a salt of a polyacrylic acid includes ALCOSORB G1
(available from Ciba Specialties). The anode can include, for
example, between 0.05 wt % and 2 wt % or between 0.1 wt % and 1 wt
% gelling agent.
[0032] A gassing inhibitor can include a metal such as bismuth,
tin, indium, or mixtures thereof in the form of alloys.
Alternatively, a gassing inhibitor can include an organic compound,
such as a phosphate ester, an ionic surfactant or a nonionic
surfactant. Examples of ionic surfactants are disclosed in, for
example, U.S. Pat. No. 4,777,100, which is hereby incorporated by
reference in its entirety.
[0033] Separator 16 can be a conventional battery separator. In
some embodiments, separator 16 can be formed of two layers of
non-woven, non-membrane material with one layer being disposed
along a surface of the other. For example, to minimize the volume
of separator 16 while providing an efficient battery, each layer of
non-woven, non-membrane material can have a basic weight of about
54 grams per square meter, a thickness of about 5.4 mils when dry
and a thickness of about 10 mils when wet. The layers can be
substantially devoid of fillers, such as inorganic particles.
[0034] In other embodiments, separator 16 can include a layer of
cellophane combined with a layer of non-woven material. The
separator also can include an additional layer of non-woven
material. The cellophane layer can be adjacent cathode 12 or the
anode. The non-woven material can contain from 78 wt % to 82 wt %
polyvinyl alcohol and from 18 wt % to 22 wt % rayon with a trace
amount of a surfactant, such as non-woven material available from
PDM under the trade name PA25.
[0035] Housing 18 can be a conventional housing commonly used in
primary alkaline batteries, such as, for example, nickel-plated
cold-rolled steel. The housing can include an inner metal wall and
an outer electrically non-conductive material such as a heat
shrinkable plastic. Optionally, a layer of conductive material can
be disposed between the inner wall and cathode 12. The layer can be
disposed along the inner surface of the inner wall, along the
circumference of cathode 12, or both. The conductive layer can be
formed, for example, of a carbonaceous material (e.g., colloidal
graphite), such as LB1000 (Timcal), Eccocoat 257 (W.R. Grace &
Co.), Electrodag 109 (Acheson Colloids Company), Electrodag EB-008
(Acheson), Electrodag 112, (Acheson) and EB0005 (Acheson). Methods
of applying the conductive layer are disclosed in, for example
Canadian Patent No. 1,263,697, which is hereby incorporated by
reference in its entirety. Optionally, a corrosion-resistant
coating can be applied to the inner wall of the housing. The
corrosion-resistant coating can include gold, titanium nitride,
titanium oxynitride, or titanium oxycarbide.
[0036] Current collector 28 can be made from a suitable metal, such
as brass. Seal 30 can be made, for example, of a nylon.
[0037] Cathode 12 includes an active cathode material, conductive
carbon particles, and electrolyte solution. Optionally, cathode 12
can also include an oxidizing additive, a gold(+3) salt, a binder,
or combinations thereof. Generally, the cathode can include, for
example, between 60% by weight and 97% by weight, between 80% by
weight and 95% by weight, or between 85% by weight and 90% by
weight active cathode material. The active cathode material can be
nickel oxyhydroxide, for example, prepared as described
hereinabove. The oxidizing additive is more readily reduced than
the active cathode material and can thereby serve as a sacrificial
additive. Examples of oxidizing additives can include sodium
hypochlorite, sodium peroxydisulfate, potassium peroxydisulfate,
potassium permanganate, barium permanganate, barium ferrate, silver
permanganate, or disilver dioxide. The gold (+3) salt can include
gold(+3) oxide, gold(+3) hydroxide, gold(+3) sulfide or gold(+3)
acetate. The amount of gold(+3) salt can range from 2 to 1000 ppm,
from 5 to 250 ppm or from 10 to 100 ppm. The gold(+3) salt can
suppress a self-discharge reaction involving oxidation of water in
the electrolyte to form oxygen gas by the nickel oxyhydroxide as
disclosed in co-pending U.S. application Ser. No. 10/022,272, which
is incorporated by reference in its entirety.
[0038] The conductive carbon particles can include graphite
particles. The graphite particles can be synthetic graphite
particles, including expanded graphite, non-synthetic, or natural
graphite, or a blend thereof. Suitable graphite particles can be
obtained from, for example, Brazilian Nacional de Grafite of
Itapecerica, MG Brazil (e.g., NdG grade MP-0702X), Superior
Graphite Co. of Chicago, Ill. (Superior ABG grade), Chuetsu
Graphite Works, Ltd. (e.g., Chuetsu grades WH-20A-and WH-20AF) of
Japan or Timcal America of Westlake, Ohio (e.g., Timcal grade
EBNB-90). The cathode can include, for example, between 2 wt % and
35 wt %, between 3 wt % and 10 wt %, or between 4 wt %, and 8 wt %
of conductive carbon particles or a blend of conductive carbon
particles.
[0039] Examples of binders can include a polymer such as
polyethylene, polyacrylamide, or a fluorocarbon resin, such as PVDF
or PTFE. An example of a polyethylene binder is sold under the
trade name COATHYLENE HA-1681 (available from Hoechst). The cathode
can include, for example, between 0.05 wt % and 5 wt %, or between
0.1 wt % and 2 wt % binder.
[0040] A portion of the electrolyte solution can be dispersed
through cathode 12, and the weight percentages provided above and
below are determined after the electrolyte solution has been
dispersed.
[0041] Batteries (e.g., button cells) including nickel oxyhydroxide
in the cathode were prepared according to the following
examples.
EXAMPLE 1
[0042] A mixture consisting of 5.0 g commercial beta-nickel
hydroxide (Tanaka Chemical Co., type Z) and 2.08 g of freshly
ground potassium hydroxide (Fluka Chemika) was prepared either
manually with a mortar and pestle or mechanically using a high
speed laboratory blade mill (Waring mixer/mill) in a dry, air-free
atmosphere in an argon-purged glovebox. The mixture was transferred
to a 1 liter glass Erlenmeyer reaction flask (Ace Glass Co.) while
still protected from air. The flask was provided with multiple
internal glass ribs to aid in tumbling and mixing of the powder
during ozonation. The ozone gas was generated using a silent
electrical discharge-type ozone generator (Ozonia OZAT.RTM. Model
CFS1A). About 70 g/hr of ozone was produced mixed with dioxygen at
an effective ozone concentration of about 10 to 12%. A total
volumetric flowrate of about 4 liters/min was obtained with an
oxygen gas inlet pressure of about 20 psi.
[0043] The ozone and dioxygen gas mixture was passed over a
controlled volume of water (about 1 ml) in a 1 liter ballast flask
connected upstream of the reaction flask in order to humidify the
ozone gas before it passed over the dry powder mixture because some
moisture is needed to initiate the oxidation process. Excessive
amounts of moisture must be avoided in order to minimize
agglomeration of the powder before oxidation can take place. Once
the reaction starts, no additional moisture is required since water
is generated as a side-product of the oxidation reaction. The
reaction flask was rotated slowly to agitate and mix the powder
thoroughly thereby ensuring uniform exposure of the powder mixture
to the ozone gas. The reaction flask was partially submerged in a
cooling bath to maintain a constant temperature of about 20.degree.
C. during ozonation. Almost immediately upon introduction of the
ozone gas into the reaction flask, the green beta-nickel hydroxide
powder turned black and formed coarse agglomerates that were broken
up by the rotation of the flask as the powder dried. Ozonation was
continued for about 4 hours. Samples were removed after about 2
hours (Example 1a) and 4 hours (Example 1b) of ozonation for
evaluation of completeness of oxidation by powder x-ray diffraction
(XRD) analysis. After 4 hours of ozonation, no un-oxidized
beta-nickel hydroxide was detectable by XRD and the predominant
product was beta-nickel oxyhydroxide. A small amount (i.e., <2
wt %) of gamma-nickel oxyhydroxide present as well.
EXAMPLE 2
[0044] A mixture consisting of 72 g cobalt hydroxide-coated
beta-nickel hydroxide (H. C. Starck) and 3 g of freshly ground
potassium hydroxide (Fluka Chemika) was prepared either manually or
mechanically as in Example 1. The mixture was treated with ozone in
the same manner as described in Example 1. Upon introduction of
ozone to the reaction vessel, the cobalt hydroxide-coated
beta-nickel hydroxide changed from gray-green in color to black and
formed coarse agglomerates that subsequently were broken up by
tumbling as the formed cobalt oxyhydroxide-coated beta-nickel
oxyhydroxide dried. XRD analysis was used to determine that
oxidation to cobalt oxyhydroxide-coated beta-nickel oxyhydroxide
was complete after a total of about 5 hours of ozonation (Example
2a). Unlike Example 1, no evidence of formation of gamma-nickel
oxyhydroxide was observed.
EXAMPLE 3
[0045] A mixture consisting of 37.5 g cobalt hydroxide-coated
alpha-nickel hydroxide containing aluminum and cobalt dopants (H.
C. Starck), 6.75 g freshly ground potassium hydroxide (Fluka
Chemika), and 0.96 g freshly ground sodium hydroxide (Aldrich, ACS
Reagent) was prepared either manually with a mortar and pestle or
mechanically using a high speed laboratory blade mill (Waring
mixer/mill) in a dry, air-free atmosphere, for example, inside an
argon-purged glovebox. The mixture was transferred to a reaction
flask inside a purged argon glovebox and initially treated with a
humidified ozone gas stream as in Example 1.
[0046] Upon introduction of ozone gas into the reaction flask, the
gray-green alpha-nickel hydroxide powder turned black and formed
coarse agglomerates that were broken up by the rotation of the
flask. After about two hours of ozonation, the powder turned from
black to a dark charcoal gray color as the powder dried. Ozonation
was continued for a total of 8 to 10 hours and samples removed
after about 2 hours (Example 3a), 6 hours (Example 3b), and 9 hours
(Example 3c) of ozonation to evaluate completeness of oxidation by
powder XRD analysis. Surprisingly, after only 2 hours of ozonation,
no un-oxidized alpha-nickel hydroxide remained.
[0047] X-Ray Diffraction Analysis
[0048] The observed values for the two-theta angles and the
corresponding d-spacings for the. (001) and (101) or (001) and
(002) diffraction lines of the starting materials and the (001) and
(002) or (003) and (006) lines of the products from Examples 1, 2,
and 3. are given in Table 1. TABLE-US-00001 TABLE 1 O.sub.3 Ex.
Time Peak 1 Peak 1 Peak 2 Peak 2 No. (hrs) 2.theta. angle (hkl) D
(.ANG.) 2.theta. angle (hkl) D (.ANG.) -- 0 18.95 001 4.679 38.55
101 2.333 1a 2 19.08 001 4.647 38.55 002 2.333 1b 4 19.08 001 4.647
38.68 002 2.326 -- 0 19.11 001 4.641 38.42 002 2.341 2a 5 19.05 001
4.654 38.42 101 2.341 -- 0 11.32 001 7.810 22.76 002 3.904 3a 2
12.56 003 7.042 25.28 006 3.520 3b 6 12.52 003 7.064 25.21 006
3.530 3c 8 12.72 003 6.953 25.40 006 3.504
[0049] The products of Example 1, Example 1a which was removed
after 2 hours of ozonation and Example 1b which was removed after 4
hours of ozonation, and the beta-nickel hydroxide starting material
were examined by XRD. The XRD powder patterns were measured and are
shown in FIG. 2. The diffraction lines of the beta-nickel hydroxide
starting material shown in FIG. 2 (curve A) corresponded closely to
those reported in the standard XRD pattern (i.e., ICDD PDF-2, No.
14-0117) for beta-niickel hydroxide. After two hours of ozonation,
the intensities of the beta-nickel hydroxide, peaks decreased and
the remaining peaks broadened substantially, as shown in FIG. 2
(curve B). Also, a low intensity peak appeared at a two-theta angle
(Cu K.alpha.) of about 12.degree. along with a low intensity broad
peak centered on a two-theta angle of about 23.degree.. These two
weak peaks corresponded to the two most intense peaks in the powder
pattern of gamma-nickel oxyhydroxide (i.e., ICDD PDF-2, No.
06-0075). After four hours of ozonation, all the characteristic
peaks of beta-nickel hydroxide disappeared completely FIG. 2 (curve
C). In addition to the very weak peaks attributed to gamma-nickel
oxyhydroxide, there remained only a broad, intense peak at a
two-theta angle of about 19.degree. and a very broad, low intensity
peak centered on a two-theta angle of about 38.degree. that could
be assigned to beta-nickel oxyhydroxide.
[0050] The XRD patterns for the oxidized product of Example 2
removed after 5 hours of ozonation (Example 2a) and the cobalt
hydroxide-coated beta-nickel hydroxide starting material were
measured. The diffraction lines of the cobalt hydroxide-coated
beta-nickel hydroxide correspond closely to those in the standard
XRD pattern for beta-nickel hydroxide (i.e., ICDD PDF-2, No.
14-0117). The XRD pattern for Example 2a showed no traces of lines
attributable to beta-nickel hydroxide and only exhibited lines
characteristic of beta-nickel oxyhydroxide as shown in FIG. 2
(curve C). No lines attributable to gamma-nickel oxyhydroxide were
observed.
[0051] The products of Example 3 that were removed after 2 hours of
ozonation (Example 3a) and after 8 hours of ozonation (Example 3c),
and the cobalt hydroxide-coated aluminum and cobalt bulk-doped
alpha-nickel hydroxide starting material were examined. The XRD
powder pattern measured for cobalt hydroxide-coated aluminum and
cobalt bulk-doped alpha-nickel hydroxide starting material FIG. 3
(curve A) corresponds closely to those reported by B. Liu, et al,
J. Appl. Electrochem., Vol. 29, 1999, pp. 855-60, and A. Sugimoto,
et al., J. Electrochem. Soc., Vol. 145, no. 4, 1999, pp. 1251-5,
each of which is incorporated by reference in its entirety, for
aluminum-substituted alpha-nickel hydroxide. Samples were removed
after 2, 4, 6, and 8 hours of ozonation. After two hours of
ozonation (Example 3a), the very intense peak at a two-theta angle
of about 11.5.degree. (003), the less intense peak at a two-theta
angle of about 22.5.degree. (006), and other weaker peaks at two
theta angles of about 35.degree. (101) and (012), 39.degree. (015),
60.5.degree. (110), and 61.7.degree. (113) characteristic of
alpha-nickel hydroxide were absent, as shown in FIG. 3 (curve B).
However, a very intense, broad peak appeared at a two-theta angle
of about 12.5.degree. as well as a somewhat less intense, broad
peak at a two-theta angle of about 25.degree.. Other broad, low
intensity peaks characteristic of a gamma-nickel oxyhydroxide phase
(i.e., ICDD PDF-2, No. 06-0075) appeared at two-theta angles of
about 38.degree., 43.5.degree., and 67.5.degree.. In addition, a
very weak, very broad peak at a two-theta angle of about 19.degree.
possibly corresponding to the most intense peak of beta-nickel
oxyhydroxide was observed. The XRD pattern for the sample removed
after 6 hours of ozonation (Example 3b) was nearly identical in
appearance to that of Example 3a except that the two most intense
diffraction peaks (i.e., 12.5.degree. and 25.degree.) had shifted
to slightly higher two-theta angles. The other peaks were too:
broad and too weak to observe the small shifts. The XRD pattern for
a sample removed after eight hours of ozonation (Example 3c) was
very similar to that for the sample removed after six hours of
ozonation (Example 3b), except that the two most intense peaks
(i.e., 12.75.degree. and 25.5.degree.) once again shifted to
slightly higher two-theta angles as shown in FIG. 3 (curve C). This
trend is readily apparent as shown in Table 1. The main ozonation
product from Example 3 was identified by XRD to be gamma-nickel
oxyhydroxide containing a trace of cobalt oxyhydroxide. The small
amount of cobalt oxyhydroxide can be formed by oxidation of the
cobalt hydroxide in the coating on the alpha-nickel hydroxide.
COMPARATIVE EXAMPLE 1
[0052] A sample of cobalt oxyhydroxide-coated gamma-nickel
oxyhydroxide prepared from a cobalt hydroxide-coated alpha-nickel
hydroxide containing aluminum and cobalt bulk dopants comparable to
that used in Example 3, except that no special precautions were
taken to exclude atmospheric air during preparation of the reaction
mixture or during ozonation. Samples were removed periodically as
in Example 3 to evaluate completeness of oxidation by powder XRD
analysis. After between 40 (Comparative Example 1a) and 48 hours
(Comparative, Example 1b) of ozonation, the oxidation reaction was
judged to have gone to completion. The XRD patterns were nearly
identical to that for Example 3c shown in FIG. 3 (curve C).
[0053] Test Cells
[0054] A portion of the beta-nickel oxyhydroxide of Example 1b was
evaluated as the active cathode material in alkaline 635-type
button cells. A cathode mixture was prepared by mixing 1.80 g
beta-nickel oxyhydroxide, 1.05 g natural graphite (Nacional de
Grafite type MP-0702x), and 0.15 g of aqueous electrolyte solution
containing 38 wt % KOH and 2 wt % ZnO with a mortar and pestle.
Cathode disks weighing nominally 0.5 g were pressed directly into a
nickel wire grid welded to the bottom of the cathode can at an
applied pressure of 10,000 pounds. A separator disk wetted with
electrolyte was placed on top the cathode disk. A plastic seal was
positioned on the anode can and 2.6 g gelled zinc slurry containing
60 wt % zinc alloy particles, 39.5 wt % electrolyte, and about 0.5
wt % gelling agent was added to the anode can. The cathode can was
positioned overlying the anode can and the cell was manually
crimped shut. Multiple button cells were fabricated and the
discharge performance evaluated at nominally high (i.e., 43 mA,
0.8C) and low (i.e., 3 mA, C/30) rates to a 0.6 V cutoff. OCV
values for cells measured immediately before discharge and specific
capacities for cells discharged at both high and low rates to a 0.8
V cutoff are given in Table 2. The reported values are the averages
for four or five individual cells. Capacity retention also was
evaluated for cells stored at 60.degree. C. for 24 hours (Example
1c). The specific capacities for cells discharged at high and low
rates after storage at 60.degree. C. for 24 hours and the
corresponding percent cumulative capacity loses relative to fresh
cells discharged at the same rates are listed in Table 2.
[0055] A portion of the cobalt oxyhydroxide coated beta-nickel
oxyhydroxide of Example 2a was evaluated as an active cathode
material in alkaline 635 button cells. A cathode mixture was
prepared in the same manner as for the un-coated beta-nickel
oxyhydroxide of Example 1b. Multiple button cells were fabricated
and discharge performance evaluated at nominally high and low rates
to a 0.8V cutoff after an 18 to 24 hour rest period at room
temperature. OCV values and specific capacities are given in Table
2. Capacity retention was evaluated for cells stored at 60.degree.
C. for 1 day (Example 2b), 7 days (Example 2c), and 14 days
(Example 2d). Specific capacities after storage and corresponding
cumulative capacity losses relative to fresh cells discharged at
the same rates are given in Table 2.
[0056] Button cells were also prepared having cathodes containing
the gamma-nickel oxyhydroxide of Example 3c. A cathode mixture was
prepared by mixing 1.80 g gamma-nickel oxyhydroxide, 1.05 g natural
graphite (Nacional de Grafite type MP-0702x), and 0.15 g of aqueous
electrolyte solution containing 38 wt % KOH and 2 wt % ZnO with a
mortar and pestle. Cathode disks weighing nominally 0.5 g were
pressed directly into a nickel wire grid welded to the bottom of
the cathode can at an applied pressure of 10,000 pounds. A
separator disk wetted with electrolyte was placed on top the
cathode disk. A plastic seal was positioned on top of the separator
and 2.6 g of a gelled zinc slurry containing 60 wt % zinc alloy
particles, 39.5 wt % electrolyte, and about 0.5 wt % gelling agent
was added to the cell. The anode can was positioned in the seal and
the button cell manually crimped shut. Multiple button cells were
fabricated and the discharge performance of fresh cells evaluated
at nominally high and low rates to a 0.8 V cutoff. OCV values
measured immediately before discharge and specific capacities for
cells discharged at high and low rates to a 0.8 V cutoff are given
in Table 2. The reported values are averaged for four or five
individual cells. Capacity retention also was evaluated for cells
stored at 60.degree. C. for 7 days (Example 3d), 14 days (Example
3e), and 28 days (Example 3f). Specific capacities after storage
and the corresponding cumulative capacity losses relative to fresh
cells discharged at the same rates are given in Table 2.
[0057] Button cells having cathodes containing the cobalt
oxyhydroxide-coated gamma-nickel oxyhydroxide of Comparative
Examples 1a and 1b gave specific capacities as well as OCV values
comparable to those of Example 3c. However, more than 5 times the
ozonation time was required to prepare the cobalt oxyhydroxide
coated gamma-nickel oxyhydroxide of Comparative Example 1b as to
prepare the cobalt oxyhydroxide coated gamma-nickel oxyhydroxide of
Example 3c. TABLE-US-00002 TABLE 2 Ex. O.sub.3 Time Storage @ OCV
Capacity @ Capacity Capacity @ Capacity No. (hrs) 60.degree. C.
(days) (V) 0.8 C. (mAhr/g) Loss (%) C./30 (mAhr/g) Loss (%) 1b 4 0
1.81 223 -- 276 -- 1c 4 1 1.72 119 47 241 13 2a 5 0 1.80 207 -- 233
-- 2b 5 1 1.72 179 14 203 13 2c 5 7 1.70 140 32 158 32 2d 5 14 1.69
119 43 127 45 3c 8 0 1.82 224 -- 281 -- 3d 8 7 1.68 208 7 233 17 3e
8 14 1.68 194 13 219 22 3f 8 28 1.67 172 23 197 30 C1a 40 0 1.77
224 -- 281 -- C1b 48 0 1.80 240 -- 280 --
[0058] The theoretical specific capacity for beta-nickel
oxyhydroxide is about 292 mAhr/g. The average value for the low
rate specific capacity of cells with cathodes containing the
beta-nickel oxyhydroxide of Example 1b is nearly 96% of the
theoretical one-electron capacity. In the absence of stabilizing
additives or a cobalt oxyhydroxide coating, the capacity retention
of the cells of Example 1c containing the beta-nickel oxyhydroxide
of Example 1b is about 58%.
[0059] Capacity retention by cells having cathodes containing
cobalt oxyhydroxide coated beta-nickel oxyhydroxide is
substantially better than for cells with cathodes containing
un-coated beta-nickel oxyhydroxide. In the absence of stabilizing
additives, capacity retention by the cells of Example 2b after 24
hours storage at 60.degree. C. was about 85%. After 14 days, the
capacity retention by the cells of Example 2d decreased to about
55%.
[0060] The capacity retention of cells with cathodes containing
cobalt oxyhydroxide coated gamma-nickel oxyhydroxide is even
greater than that for cells with cathodes containing cobalt
oxyhydroxide coated beta-nickel oxyhydroxide. Capacity retention
can be improved further by incorporating very small amounts (e.g.,
10-100 ppm) of a variety of gold(+3) salts in the cathode as
disclosed in co-pending U.S. application Ser. No. 10/022,272, which
is incorporated by reference in its entirety.
[0061] Other embodiments are within the claims.
* * * * *