U.S. patent application number 10/003916 was filed with the patent office on 2002-05-09 for high density cobalt-manganese coprecipitated nickel hydroxide and process for its production.
This patent application is currently assigned to Tanaka Chemical Corporation. Invention is credited to Iida, Toyoshi, Ito, Hiroyuki, Shimakawa, Mamoru, Usui, Takeshi.
Application Number | 20020053663 10/003916 |
Document ID | / |
Family ID | 18813185 |
Filed Date | 2002-05-09 |
United States Patent
Application |
20020053663 |
Kind Code |
A1 |
Ito, Hiroyuki ; et
al. |
May 9, 2002 |
High density cobalt-manganese coprecipitated nickel hydroxide and
process for its production
Abstract
The present invention provides high density cobalt-manganese
coprecipitated nickel hydroxide, particularly having a tapping
density of 1.5 g/cc or greater, and a process for its production
characterized by continuous supply of an aqueous solution of a
nickel salt which contains a cobalt salt and a manganese salt, of a
complexing agent and of an alkali metal hydroxide, into a reactor
either in an inert gas atmosphere or in the presence of a reducing
agent, continuous crystal growth and continuous removal.
Inventors: |
Ito, Hiroyuki; (Fukui-shi,
JP) ; Usui, Takeshi; (Fukui-shi, JP) ;
Shimakawa, Mamoru; (Fukui-shi, JP) ; Iida,
Toyoshi; (Fukui-shi, JP) |
Correspondence
Address: |
Paul D. Greeley, Esq.
Ohlandt, Greeley,Ruggiero & Perle, L.L.P.
10th Floor
One Landmark Square
Stamford
CT
06901-2682
US
|
Assignee: |
Tanaka Chemical Corporation
Fukui-ken
JP
|
Family ID: |
18813185 |
Appl. No.: |
10/003916 |
Filed: |
November 2, 2001 |
Current U.S.
Class: |
252/518.1 |
Current CPC
Class: |
C01G 53/006 20130101;
C01P 2004/01 20130101; H01B 1/08 20130101; H01M 4/525 20130101;
C01P 2006/12 20130101; Y02E 60/10 20130101; C01P 2004/03 20130101;
H01M 4/505 20130101; C01P 2004/61 20130101; C01P 2006/10 20130101;
C01G 51/006 20130101; C01P 2004/62 20130101; C01P 2006/11 20130101;
C01P 2006/32 20130101; H01M 10/0525 20130101 |
Class at
Publication: |
252/518.1 |
International
Class: |
H01B 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 6, 2000 |
JP |
2000-337873 |
Claims
What is claimed is:
1. High density cobalt-manganese coprecipitated nickel hydroxide
with a tapping density of 1.5 g/cc or greater.
2. High density cobalt-manganese coprecipitated nickel hydroxide
according to claim 1, characterized in that, where said
cobalt-manganese coprecipitated nickel hydroxide is represented as
(Ni.sub.(1-x-y)Co.sub.x- Mn.sub.y)(OH).sub.2,
1/10.ltoreq.x.ltoreq.1/3 and 1/20.ltoreq.y.ltoreq.1/3- .
3. A process for production of high density cobalt-manganese
coprecipitated nickel hydroxide of claim 1, characterized by
continuous supply of an aqueous solution of a nickel salt which
contains a cobalt salt and a manganese salt, of a complexing agent
and of an alkali metal hydroxide, into a reactor either in an inert
gas atmosphere or in the presence of a reducing agent, continuous
crystal growth and continuous removal.
4. The process of claim 3 wherein said reducing agent is hydrazine.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to high density
cobalt-manganese coprecipitated nickel hydroxide with excellent
charge/discharge cycle properties and high temperature stability,
which is suitable as a positive electrode active material for a
lithium ion secondary battery, and to a process for its
production.
BACKGROUND OF THE INVENTION
[0002] Recently, attempts have been made to add other components to
nickel hydroxide used as the starting material for production of
lithium nickel oxide, for the purpose of including additional
components with lithium nickel oxide for use as the positive
electrode active material of lithium ion secondary batteries in
order to improve their charge/discharge cycle properties and high
temperature stability (JP-A 10-316431).
[0003] However, with the conventional process it has been difficult
to obtain nickel hydroxide particles containing cobalt and
manganese as the additional components while still maintaining
density sufficient for current requirements.
[0004] The above-mentioned conventional production process gives
particles that are inadequate for use in the positive electrode of
a lithium ion secondary battery, and thus it has become an
important goal to develop high density nickel hydroxide with a high
cobalt and manganese content that exhibits a stable high
utilization rate at high temperatures and low cycle
deterioration.
SUMMARY OF THE INVENTION
[0005] As a result of diligent research directed toward achieving
this goal, the present inventors have completed the present
invention upon finding that it is possible to obtain high density
cobalt-manganese coprecipitated nickel hydroxide by continuously
supplying a complexing agent and an alkali metal hydroxide to an
aqueous solution of a nickel salt containing a cobalt salt and a
manganese salt while adequately stirring in an aqueous solution
either in an inert gas atmosphere or in the presence of an
appropriate reducing agent, and accomplishing continuous crystal
growth and continuous removal.
[0006] In other words, the present invention relates to high
density cobalt-manganese coprecipitated nickel hydroxide with a
tapping density of 1.5 g/cc or greater.
[0007] The invention further relates to high density
cobalt-manganese coprecipitated nickel hydroxide characterized in
that, where the cobalt-manganese coprecipitated nickel hydroxide is
represented as (Ni.sub.(1-x-y)Co.sub.xMn.sub.y)(OH).sub.2,
1/10.ltoreq.x.ltoreq.1/3 and 1/20.ltoreq.y.ltoreq.1/3.
[0008] The invention still further relates to a process for
production of high density cobalt-manganese coprecipitated nickel
hydroxide, characterized by continuous supply of an aqueous
solution of a nickel salt which contains a cobalt salt and a
manganese salt, of a complexing agent and of an alkali metal
hydroxide, into a reactor either in an inert gas atmosphere or in
the presence of a reducing agent, continuous crystal growth and
continuous removal. It particularly relates to this process wherein
the reducing agent is hydrazine.
[0009] The invention also includes
Li(Ni.sub.(1-x-y)Co.sub.xMn.sub.y)O.sub- .2 obtained by calcining a
cobalt-manganese coprecipitated nickel hydroxide according to the
invention with an appropriate lithium salt.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is an electron micrograph of high density
cobalt-manganese coprecipitated nickel hydroxide according to the
invention.
DETAILED DESCRIPTION OF THE INVENTION
High Density Cobalt-manganese Coprecipitated Nickel Hydroxide
[0011] The cobalt-manganese coprecipitated nickel hydroxide of the
invention is characterized by having high density, and
specifically, a density of 1.5 g/cc or greater. The specific
surface area of the cobalt-manganese coprecipitated nickel
hydroxide of the invention is in the range of 8-20 m.sup.2/g, and
as shown in FIG. 1 it is spherical with a mean particle size in the
range of 5-20 .mu.m.
[0012] Although the content of the cobalt and manganese as
additional components is not particularly restricted, if
represented by (Ni.sub.(1-x-y)Co.sub.xMn.sub.y)(OH).sub.2 the
ranges are preferably 1/10.ltoreq.x.ltoreq.1/3 and
1/20.ltoreq.y.ltoreq.1/3.
Production Process
[0013] The production process for the cobalt-manganese
coprecipitated nickel hydroxide of the invention accomplishes
production of nickel hydroxide with high density of coprecipitated
cobalt and manganese by continuous supply of an aqueous solution of
a nickel salt containing a cobalt salt (cobalt (II) ion) and a
manganese salt (manganese (II) ion), of a complexing agent and of
an alkali metal hydroxide, to a reactor with adequate stirring
either in an inert gas atmosphere or in the presence of a reducing
agent, continuous crystal growth and continuous removal of the
resulting precipitate.
[0014] Here, the salt concentration, complexing agent
concentration, pH and temperature in the reactor are kept within a
fixed range to satisfactorily control the powder properties, such
as the crystallinity, tapping density, specific surface area,
particle size, etc.
[0015] Specifically, there is obtained high density
cobalt-manganese coprecipitated nickel hydroxide wherein, as
represented by (Ni.sub.(1-x-y)Co.sub.xMn.sub.y)(OH).sub.2,
1/10.ltoreq.x.ltoreq.1/3 and 1/20.ltoreq.y.ltoreq.1/3, the tapping
density is 1.5 g/cc or greater, the specific surface area is 8-30
m.sup.2/g and the mean particle size is 5-20 .mu.m.
[0016] For the high density cobalt-manganese coprecipitated nickel
hydroxide, the salt concentration in the vessel is preferably kept
in the range of 50-200 mS/cm .+-.5 mS/cm and the ammonium ion
concentration is preferably kept in the range of 1-10 g/L .+-.0.5
g/L. The reaction pH is preferably kept in the range of 11.0-13.0
.+-.0.05, and the reaction temperature is preferably kept in the
range of 25-80.degree. C. .+-.0.5.degree. C.
[0017] As salt concentration adjustors there may be mentioned
sodium chloride, potassium chloride, sodium sulfate, potassium
sulfate, ammonium chlorate, ammonium sulfate and the like. As
calcium salts there may be used nitrate, acetate or oxalate
salts.
[0018] The production process of the invention is based on the high
density nickel hydroxide production process described in JP-A
10-97856 but is characterized by further adding an appropriate
reducing agent. That is, while adequate stirring is usually
necessary, this results in inclusion of air, etc. which causes
partial oxidation of the unstable cobalt (II) ion or manganese (II)
ion and prevents a product with sufficient density from being
obtained. In order to control such oxidation, the production
process is carried out either in an inert gas atmosphere or in the
presence of a reducing agent. The added reducing agent is not
particularly restricted, but hydrazine is preferred.
[0019] In most cases when precipitating solid crystals from aqueous
solution, a high concentration gradient results in abundant
precipitation of fine particles. That is, the mechanism by which
solid crystals precipitate from aqueous solution involves the
aqueous solution passing from
presaturation.fwdarw.saturation.fwdarw.supersaturation.fwdarw.crysta-
l precipitation. Growth of crystals requires this mechanism to be
effected as slowly as possible, and a low concentration gradient
near saturation is necessary for this purpose. Nevertheless, the
solubility curves for hydroxides of nickel, cobalt and manganese
vary considerably according to the pH. In other words, the metal
ion concentration gradient is very large with respect to the pH.
Only production of fine particles therefore can be expected by
ordinary methods. According to the invention, however, the metal
ions are in a complex salt with ammonium so that the concentration
gradient of the metal ions with respect to the pH is reduced in
aqueous solution to achieve growth of particles.
[0020] With pH control alone, decomposition and evaporation of
ammonia alters the ammonium ion concentration in the solution, such
that generation of crystal nuclei produced from the ammonium
complex salt becomes unstable. Only by controlling the ammonium ion
concentration of the solution does generation of crystal nuclei
become constant, so that uniform growth of particles occurs. In
order to maintain such a mechanism, the ammonium ion source and
alkali metal hydroxide must consistently match the necessary amount
of metal ion, and therefore the reaction process is preferably
carried out in a continuous manner. By speeding up the stirring
rate, an abrading effect also occurs between the particles, and
this repeated abrasion and growth result in fluidized, spherical
high density particles.
[0021] The ammonium ion source for the reaction as a complexing
agent according to the invention is used as a reaction
intermediate, as represented by reaction formulas (1) and (2).
Here, the nickel salt, ammonium ion source and alkali metal
hydroxide are nickel sulfate, ammonia and sodium hydroxide,
respectively. (Cobalt and manganese are omitted in order to
simplify the formulas, but they likewise progress through ammonium
complex salts.) As is apparent from the formulas, 4 equivalents of
ammonia are not necessary, as about 0.5 equivalent at most is
sufficient.
NiSO.sub.4+4NH.sub.3+2NaOH.fwdarw.Ni(NH.sub.3).sub.4(OH).sub.2+Na.sub.2SO.-
sub.4 (1)
Ni(NH.sub.3).sub.4(OH).sub.2.fwdarw.Ni(OH).sub.2+4NH.sub.3 (2)
EXAMPLE 1
[0022] After placing 450 L of water in a 500 L cylindrical reactor
equipped with an overflow pipe and a stirrer provided with two
250.phi. propeller type stirring blades, a 30% sodium hydroxide
solution was added to a pH of 12.6 and the temperature was kept at
50.degree. C. while stirring at a speed of 320 rpm.
[0023] Next there were simultaneously added to the reactor in a
continuous manner a solution containing a mixture of 1.7 mol/L
nickel sulfate solution, 1.5 mol/L cobalt sulfate solution and 1.1
mol/L manganese sulfate aqueous solution in a volume ratio of
35:20:9 at a flow rate of 200 cc/min, a 6 mol/L ammonium sulfate
solution at 63 cc/min and a 1 wt % hydrazine aqueous solution at 10
cc/min.
[0024] Also, 30% sodium hydroxide was intermittently added until
the solution in the reactor reached a pH of 12.6, to form
cobalt-manganese coprecipitated nickel hydroxide particles.
[0025] After 120 hours when the reactor reached a steady state, the
cobalt-manganese coprecipitated nickel hydroxide particles were
continuously removed for 24 hours from the overflow pipe and
washed, filtered and dried at 100.degree. C. for 15 hours to obtain
cobalt-manganese coprecipitated nickel hydroxide dry powder with a
component ratio of Ni:Co:Mn=60:30:10.
[0026] The tapping density of the obtained cobalt-manganese
coprecipitated nickel hydroxide powder was measured in the manner
described below.
[0027] Sample preparation: The cobalt-manganese coprecipitated
nickel hydroxide powder obtained above was used in the manner
described below.
[0028] The mass [A] of a 20 mL cell [C] was measured, and the
crystals were allowed to naturally fall into the cell through a 48
mesh filter to fill it. The mass [B] and filling volume [D] of the
cell were measured after tapping 200 times using a "TAP DENSER
KYT-3000" by Seishin Enterprise Co., Ltd. with a mounted 4 cm
spacer. The following equations were used for calculation.
[0029] Tapping density=(B-A)/D g/ml
[0030] Bulk density=(B-A)/C g/ml
[0031] Measurement results: Tapping density=1.91 g/cc
EXAMPLE 2
[0032] Cobalt-manganese coprecipitated nickel hydroxide with a
component ratio of Ni:Co:Mn=50:30:20 was produced and the tapping
density thereof measured under the same conditions as Example 1,
except that the nickel sulfate solution, cobalt sulfate solution
and manganese sulfate solution were mixed in a volume ratio of
30:20:18 and the pH of the reaction solution used to form the
cobalt-manganese coprecipitated nickel hydroxide particles was
12.4. The tapping density was 1.71 g/cc.
EXAMPLE 3
[0033] After placing 13 L of water in a 15 L cylindrical reactor
equipped with an overflow pipe and a stirrer provided with one
70.phi. paddle type stirring blade, a 30% sodium hydroxide solution
was added to a pH of 10.9 and the temperature was kept at
50.degree. C. while stirring at a speed of 1000 rpm. Nitrogen gas
was also continuously supplied to the reactor at a flow rate of 0.5
L/min, and the atmosphere in the reactor was replaced with a
nitrogen atmosphere. Next there were simultaneously added to the
reactor in a continuous manner a solution containing a mixture of
1.7 mol/L nickel sulfate solution, 1.5 mol/L cobalt sulfate
solution and 1.1 mol/L manganese sulfate aqueous solution in a
volume ratio of Ni:Co:Mn=1:1:1 (molar ratio) at a flow rate of 12
cc/min and a 6 mol/L ammonium sulfate solution at 1.2 cc/min. Also,
30% sodium hydroxide was intermittently added until the solution in
the reactor reached a pH of 10.9, to form cobalt-manganese
coprecipitated nickel hydroxide particles. After 120 hours when the
reactor reached a steady state, the cobalt-manganese coprecipitated
nickel hydroxide particles were continuously removed for 24 hours
from the overflow pipe and washed, filtered and dried at
100.degree. C. for 15 hours to obtain cobalt-manganese
coprecipitated nickel hydroxide dry powder with a component ratio
of Ni:Co:Mn=1:1:1. The tapping density was 1.82 g/cc.
COMPARATIVE EXAMPLE 1
[0034] After placing 450 L of water in a 500 L cylindrical reactor
equipped with an overflow pipe and a stirrer provided with one
250.phi. propeller type stirring blade, a 30% sodium hydroxide
solution was added to a pH of 12.6 and the temperature was kept at
50.degree. C. while stirring at a speed of 350 rpm. Next there were
simultaneously added to the reactor in a continuous manner a
solution containing a mixture of 1.7 mol/L nickel sulfate solution,
1.5 mol/L cobalt sulfate solution and 1.1 mol/L manganese sulfate
aqueous solution in a volume ratio of 35:20:9 at a flow rate of 200
cc/min and a 6 mol/L ammonium sulfate solution at 63 cc/min. Also,
30% sodium hydroxide was intermittently added until the solution in
the reactor reached a pH of 12.6, to form cobalt-manganese
coprecipitated nickel hydroxide particles. After 120 hours when the
reactor reached a steady state, the cobalt-manganese coprecipitated
nickel hydroxide particles were continuously removed for 24 hours
from the overflow pipe and washed, filtered and dried at
100.degree. C. for 15 hours to obtain cobalt-manganese
coprecipitated nickel hydroxide dry powder with a component ratio
of Ni:Co:Mn=60:30:10. The tapping density was 1.40 g/cc.
COMPARATIVE EXAMPLE 2
[0035] Cobalt-manganese coprecipitated nickel hydroxide with a
component ratio of Ni:Co:Mn=50:30:20 was produced and the tapping
density thereof measured under the same conditions as Comparative
Example 1, except that the nickel sulfate solution, cobalt sulfate
solution and manganese sulfate solution were mixed in a volume
ratio of 30:20:18 and the pH of the reaction solution used to form
the cobalt-manganese coprecipitated nickel hydroxide particles was
12.4. The tapping density was 1.33 g/cc.
EFFECT OF THE INVENTION
[0036] According to the present invention it is possible to obtain
high density cobalt-manganese coprecipitated nickel hydroxide
having high density, and particularly a tapping density of 1.5 g/cc
or greater, by continuous supply of an aqueous solution of a nickel
salt which contains a cobalt salt and a manganese salt, of a
complexing agent and of an alkali metal hydroxide, into a reactor
either in an inert gas atmosphere or in the presence of a reducing
agent, continuous crystal growth and continuous removal.
* * * * *