U.S. patent application number 14/413809 was filed with the patent office on 2015-05-21 for doped nickelate compounds.
The applicant listed for this patent is FARADION LIMITED. Invention is credited to Jeremy Barker, Richard Heap.
Application Number | 20150137031 14/413809 |
Document ID | / |
Family ID | 46766428 |
Filed Date | 2015-05-21 |
United States Patent
Application |
20150137031 |
Kind Code |
A1 |
Barker; Jeremy ; et
al. |
May 21, 2015 |
DOPED NICKELATE COMPOUNDS
Abstract
The invention relates to novel materials of the formula:
A.sub.1-.delta.M.sup.1.sub.vM.sup.2.sub.wM.sup.3.sub.xM.sup.4.sub.yM.sup.-
5.sub.zO.sub.2 wherein A comprises either lithium or a mixed alkali
metal in which lithium is the major constituent; M.sup.1 is nickel
in oxidation state +2 M.sup.2 comprises a metal in illation state
+4 selected from one or more of manganese, titanium and zirconium;
M.sup.3 comprises a metal in oxidation state +2, selected from one
or more of magnesium, calcium, copper, zinc and cobalt; M.sup.4
comprises a metal in oxidation state +4, selected from one or more
of titanium, manganese and zirconium; M.sup.5 comprises a metal in
oxidation state +3, selected from one or more of aluminium, iron,
cobalt, molybdenum, chromium, vanadium, scandium and yttrium;
wherein 0.ltoreq..delta..ltoreq.0.1; V is in the range
0<V<0.5; W is in the range 0<W.ltoreq.0.5; X is in the
range 0.ltoreq.X<0.5; Y is in the range 0.ltoreq.Y<0.5; Z is
.gtoreq.0; wherein when M.sup.5=cobalt then X.gtoreq.0.1; and
further wherein V+W+X+Y+Z=1. Such materials are useful, for
example, as electrode materials in lithium ion battery
applications.
Inventors: |
Barker; Jeremy; (Chipping
Norton, GB) ; Heap; Richard; (Oxford, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FARADION LIMITED |
Sheffield |
|
GB |
|
|
Family ID: |
46766428 |
Appl. No.: |
14/413809 |
Filed: |
July 10, 2013 |
PCT Filed: |
July 10, 2013 |
PCT NO: |
PCT/GB2013/051822 |
371 Date: |
January 9, 2015 |
Current U.S.
Class: |
252/182.1 |
Current CPC
Class: |
H01M 4/525 20130101;
H01M 4/505 20130101; C01P 2002/72 20130101; H01M 10/054 20130101;
Y02E 60/10 20130101; H01M 10/0525 20130101; C01P 2006/40 20130101;
C01G 53/42 20130101; C01G 53/50 20130101; C01G 53/66 20130101; C01P
2002/50 20130101 |
Class at
Publication: |
252/182.1 |
International
Class: |
H01M 4/505 20060101
H01M004/505; H01M 10/0525 20060101 H01M010/0525; C01G 53/00
20060101 C01G053/00; H01M 4/525 20060101 H01M004/525 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 10, 2012 |
GB |
1212261.0 |
Claims
1. A compound of the formula:
A.sub.1-.delta.M.sup.1.sub.VM.sup.2.sub.WM.sup.3.sub.XM.sup.4.sub.YM.sup.-
5.sub.ZO.sub.2 wherein A comprises either lithium or a mixed alkali
metal in which lithium is the major constituent; M.sup.1 is nickel
in oxidation state +2 M.sup.2 comprises a metal in oxidation state
+4 selected from one or more of manganese, titanium and zirconium;
M.sup.3 comprises a metal in oxidation state +2, selected from one
or more of magnesium, calcium, copper, zinc and cobalt; M.sup.4
comprises a metal in oxidation state +4, selected from one or more
of titanium, manganese and zirconium; M.sup.5 comprises a metal in
oxidation state +3, selected from one or more of aluminum, iron,
cobalt, molybdenum, chromium, vanadium, scandium and yttrium;
wherein 0.ltoreq..delta..ltoreq.0.1; V is in the range
0<V<0.5; W is in the range 0<W.ltoreq.0.5; X is in the
range 0.ltoreq.X<0.5; Y is in the range 0.ltoreq.Y<0.5; Z is
.gtoreq.0; wherein when M.sup.5=cobalt then X.gtoreq.0.1; and
further wherein V+W+X+Y+Z=1.
2. A compound according to claim 1 wherein V is in the range
0.1.ltoreq.V.ltoreq.0.45; W is in the range 0<W.ltoreq.0.5; X is
in the range 0.ltoreq.X<0.5; Y is in the range
0.ltoreq.Y<0.5; Z is .gtoreq.0; and wherein V+W+X+Y+Z=1.
3. A compound according to claim 1 wherein V is in the range
0.3.ltoreq.V.ltoreq.0.45; W is in the range
0.1.ltoreq.W.ltoreq.0.5; X is in the range 0.05.ltoreq.X<0.45; Y
is in the range 0.ltoreq.Y.ltoreq.0.45; Z is .gtoreq.0; and wherein
V+W+X+Y+Z=1.
4. A compound according to claim 1, wherein
M.sup.2.noteq.M.sup.4.
5. A compound according to claim 1 of the formula:
LiNi.sub.0.5-xMn.sub.0.5-xCa.sub.xTi.sub.xO.sub.2,
LiNi.sub.0.5-xMn.sub.0.5-xMg.sub.xTi.sub.xO.sub.2
LiNi.sub.0.5-xTi.sub.0.5-xMg.sub.xMn.sub.xO.sub.2 and
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167Mg.sub.0.1583Mn.sub.0.2083O.sub.2.
6. An electrode comprising an active compound according to claim
1.
7. An electrode according to claim 6 used in conjunction with a
counter electrode and one or more electrolyte materials.
8. An electrode according to claim 7 wherein the electrolyte
material comprises an aqueous electrolyte material.
9. An electrode according to claim 7 wherein the electrolyte
material comprises a non-aqueous electrolyte.
10. An energy storage device comprising an electrode according to
claim 6.
11. An energy storage device according to claim 10 suitable for use
as one or more of the following: alkali metal ion cell; an alkali
metal cell; a non-aqueous electrolyte alkali metal ion cell; and an
aqueous electrolyte alkali metal ion cell, wherein the alkali metal
is lithium alone or a mixture of lithium and one or more other
alkali metals in which lithium is the major alkali metal
constituent in the mixture.
12. A rechargeable battery comprising an electrode according to
claim 6.
13. An electrochemical device comprising an electrode according to
claim 6.
14. An electrochromic device comprising an electrode according
claim 6.
15. A method of preparing the compounds according to claim 1
comprising the steps of: a) mixing the starting materials together,
b) heating the mixed starting materials in a furnace at a
temperature of between 400.degree. C. and 1500.degree. C., for
between 2 and 20 hours; and c) allowing the reaction product to
cool.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to novel doped nickelate
compounds, their method of preparation, to novel electrodes which
utilise an active material that comprises said doped nickelate
compounds, and to the use of these electrodes, for example in an
energy storage device.
BACKGROUND OF THE INVENTION
[0002] Lithium-ion battery technology has enjoyed a lot of
attention in recent years and provides the preferred portable
battery for most electronic devices in use today. Such batteries
are "secondary" or rechargeable which means that they are capable
of undergoing multiple charge/discharge cycles. Typically,
lithium-ion batteries are prepared using one or more lithium
electrochemical cells containing electrochemically active
materials. Such cells comprise an anode (negative electrode), a
cathode (positive electrode) and an electrolyte material. When a
lithium-ion battery is charging, Li.sup.+ ions de-intercalate from
the cathode and insert into the anode. Meanwhile charge balancing
electrons pass from the cathode through the external circuit
containing the charger and into the anode of the battery. During
discharge the same process occurs but in the opposite
direction.
[0003] Various electrochemically active materials have been
suggested for use as the cathode materials, for example
LiCoO.sub.2, LiMn.sub.2O.sub.4 and LiNiO.sub.2, see U.S. Pat. No.
5,135,732 and U.S. Pat. No. 4,246,253. However these materials
exhibit problems, for example cycle fading (depletion in charge
capacity over repeated charge/discharge cycles), which make them
commercially unattractive. Attempts to address cycle fading have
led to lithium metal phosphate and lithium metal fluorophosphates
becoming favourable materials. Such materials were first reported
in U.S. Pat. No. 6,203,946, U.S. Pat. No. 6,387,568, and by
Goodenough et al. in "Phospho-olivines as Positive-Electrode
Materials for Rechargeable Lithium Batteries", Journal of
Electrochemical Society, (1997) No. 144, pp 1188-1194. Many workers
have tried to provide economical and reproducible synthesis methods
for phosphate-containing materials, especially for high performance
(optimised) phosphate-containing materials, and review of the prior
art methods which describe the preparation of one particular
lithium metal phosphate, namely, lithium iron phosphate
(LiFePO.sub.4), is given by X. Zhang et al in "Fabrication and
Electrochemical Characteristics of LiFePO.sub.4 Powders for
Lithium-Ion Batteries", KONA Powder and Particle Journal No. 28
(2010) pp 50-73. As this review demonstrates, a lot of effort has
been expended since lithium iron phosphate was first identified in
1997, to find the most expedient method for producing a
LiFePO.sub.4 material with the best all round performance.
[0004] Work is now being undertaken to find even more efficient
electrochemically active materials, which have large charge
capacity, are capable of good cycling performance, highly stable,
and of low toxicity and high purity. Of course, to be commercially
successful, the cathode materials must also be easily and
affordably produced. This long list of requirements is difficult to
fulfil but it is understood from the literature that the active
materials which are most likely to succeed are those with small
particle size and narrow size distribution, with an optimum degree
of crystallinity, a high specific surface area, and with uniform
morphology. The present Applicant has also now conducted work which
demonstrates that electrochemical activity is further optimised
when the active material includes metal constituents with certain
defined oxidation states.
[0005] The present invention aims to provide novel compounds.
Further the present invention aims to provide a cost effective
electrode that contains an active material that is straightforward
to manufacture and easy to handle and store. Another aim of the
present invention is to provide an electrode that has a high
initial specific discharge capacity and which is capable of being
recharged multiple times without significant loss in charge
capacity.
[0006] Therefore, the first aspect of the present invention
provides compounds of the formula:
A.sub.1-.delta.M.sup.1.sub.VM.sup.2.sub.WM.sup.3.sub.xM.sup.4.sub.YM.sup-
.5.sub.ZO.sub.2 [0007] wherein [0008] A comprises one or more
alkali metals selected from lithium or a mixture of two or more
alkali metals in which lithium is the major constituent; [0009]
M.sup.1 is nickel in oxidation state +2 [0010] M.sup.2 comprises a
metal in oxidation state +4 selected from one or more of manganese,
titanium and zirconium; [0011] M.sup.3 comprises a metal in
oxidation state +2, selected from one or more of magnesium,
calcium, copper, zinc and cobalt; [0012] M.sup.4 comprises a metal
in oxidation state +4, selected from one or more of titanium,
manganese and zirconium; [0013] M.sup.5 comprises a metal in
oxidation state +3, selected from one or more of aluminium, iron,
cobalt, molybdenum, chromium, vanadium, scandium and yttrium;
[0014] wherein [0015] 0.ltoreq..UPSILON..ltoreq.0.1; [0016] V is in
the range 0<V<0.5; [0017] W is in the range
0<W.ltoreq.0.5; [0018] X is in the range 0.ltoreq.X<0.5;
[0019] Y is in the range 0.ltoreq.Y<0.5; [0020] Z is .gtoreq.0;
[0021] wherein when M.sup.5=cobalt then X.gtoreq.0.1; [0022] and
further wherein V+W+X+Y+Z=1.
[0023] The preferred alkali metal used in the compounds of present
invention is lithium; this may either be used alone or as a mixture
with sodium and/or potassium. In the case where the lithium is used
with other alkali metals then preferably lithium is the major
alkali metal constituent in the mixture.
[0024] Preferably the present invention provides a compound of the
above formula wherein V is in the range 0.1.ltoreq.V.ltoreq.0.45; w
is in the range 0<W.ltoreq.0.5; x is in the range
0.ltoreq.X<0.5; Y is in the range 0.ltoreq.Y<0.5; Z is
.gtoreq.0; and wherein V+W+X+Y+Z=1.
[0025] Further preferably the present invention provides a compound
of the above formula wherein V is in the range
0.3.ltoreq.V.ltoreq.0.45; W is in the range
0.1.ltoreq.W.ltoreq.0.5; X is in the range 0.05.ltoreq.X<0.45; Y
is in the range 0.ltoreq.Y.ltoreq.0.45; Z is .gtoreq.0; and wherein
V+W+X+Y+Z=1.
[0026] In particularly preferred compounds of the above formula, V
is in the range 0.3.ltoreq.V<0.45; W is in the range
0<W.ltoreq.0.5; X is in the range 0.ltoreq.X.ltoreq.0.3; Y is in
the range 0.ltoreq.Y.ltoreq.0.4; and Z is in the range
0.ltoreq.Z.ltoreq.0.5.
[0027] In another preferred group of active compounds of the above
formula: [0028] V is in the range 0<V<0.5; [0029] W is in the
range 0<W.ltoreq.0.5; [0030] X is in the range
0.ltoreq.X<0.5; [0031] Y is in the range 0.ltoreq.Y<0.5;
[0032] Z is .gtoreq.0; [0033] wherein when Z>0 then X.gtoreq.0.1
[0034] and further wherein V+W+X+Y+Z=1.
[0035] Compounds in which .delta.=0.05 are especially
preferred.
[0036] In additionally preferred compounds of the present invention
M.sup.2.noteq.M.sup.4.
[0037] Especially preferred compounds of the present invention
include:
LiNi.sub.0.5-xMn.sub.0.5-xCu.sub.xTi.sub.xO.sub.2;
LiNi.sub.0.5-xMn.sub.0.5-xCa.sub.xTi.sub.xO.sub.2;
LiNi.sub.0.5-xMn.sub.0.5-xMg.sub.xTi.sub.xO.sub.2;
LiNi.sub.0.5-xTi.sub.0.5-xMg.sub.xMn.sub.xO.sub.2; and
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167 Mg.sub.0.1583
Mn.sub.0.2083O.sub.2
[0038] In a second aspect, the present invention provides an
electrode comprising an active compound of the formula:
A.sub.1-.delta.M.sup.1.sub.VM.sup.2.sub.WM.sup.3.sub.XM.sup.4.sub.YM.sup-
.5.sub.Z [0039] wherein [0040] A comprises one or more alkali
metals selected from lithium or a mixed alkali metal in which
lithium is the major constituent; [0041] M.sup.1 is nickel in
oxidation state +2 [0042] M.sup.2 comprises a metal in oxidation
state +4 selected from one or more of manganese, titanium and
zirconium; [0043] M.sup.3 comprises a metal in oxidation state +2,
selected from one or more of magnesium, calcium, copper, zinc and
cobalt; [0044] M.sup.4 comprises a metal in oxidation state +4,
selected from one or more of titanium, manganese and zirconium;
[0045] M.sup.5 comprises a metal in oxidation state +3, selected
from one or more of aluminium, iron, cobalt, molybdenum, chromium,
vanadium, scandium and yttrium; [0046] wherein [0047]
0.ltoreq..delta..ltoreq.0.1; [0048] V is in the range
0<V<0.5; [0049] W is in the range 0<W.ltoreq.0.5; [0050] X
is in the range 0.ltoreq.X<0.5; [0051] Y is in the range
0.ltoreq.Y<0.5; [0052] Z is .gtoreq.0; [0053] wherein when
M.sup.5=cobalt then X.gtoreq.0.1; [0054] and further wherein
V+W+X+Y+Z=1.
[0055] Preferably the electrode of the present invention comprises
an active compound of the above formula, wherein V is in the range
0.1.ltoreq.V.ltoreq.0.45; w is in the range 0<W.ltoreq.0.5; x is
in the range 0.ltoreq.X<0.5; Y is in the range
0.ltoreq.Y<0.5; Z is .gtoreq.0; and wherein V+W+X+Y+Z =1.
[0056] Further preferably the electrode of the present invention
comprises an active compound of the above formula, wherein V is in
the range 0.3.ltoreq.V.ltoreq.0.45; W is in the range
0.1.ltoreq.W.ltoreq.0.5; X is in the range 0.05.ltoreq.X<0.45; Y
is in the range 0.ltoreq.Y.ltoreq.0.45; Z is .gtoreq.0; and wherein
V+W +X+Y+Z=1.
[0057] Particularly preferred electrodes of the present invention
comprise an active compound of the above formula, wherein V is in
the range 0.3.ltoreq.V<0.45; W is in the range
0<W.ltoreq.0.5; X is in the range 0.ltoreq.X.ltoreq.0.3; Y is in
the range 0.ltoreq.Y.ltoreq.0.4; and Z is in the range
0.ltoreq.Z.ltoreq.0.5.
[0058] In another preferred embodiment of the present invention the
electrode comprises a group of active compounds of the above
formula: [0059] V is in the range 0<V<0.5; [0060] W is in the
range 0<W.ltoreq.0.5; [0061] X is in the range
0.ltoreq.X<0.5; [0062] Y is in the range 0 Y<0.5; [0063] Z is
.gtoreq.0; [0064] wherein when Z>0 then X.gtoreq.0.1 [0065] and
further wherein V+W+X+Y+Z=1.
[0066] The Applicant has observed that if NiO is present as an
impurity phase in samples of the active compounds, then this has a
detrimental effect on the electrochemical performance. NiO may be
formed during the process of charging the electrode; at this time
Ni2+ can be oxidized, using up energy that would normally be used
to charge the active material. This is not only an irreversible
reaction, but also has a detrimental effect on the cycling
performance, resulting in a drop in capacity upon electrochemical
cycling. The formation of NiO by this route is found to be
minimised by reducing the amount of alkali metal in the active
compound and is the purpose for compounds of the invention which
have less than 1 unit of alkali metal.
[0067] Electrodes comprising active compounds of the above formula
in which .delta.=0.05, are highly beneficial.
[0068] Additionally preferred electrodes of the present invention
comprise an active compound as described above wherein
M.sup.2.noteq.M.sup.4.
[0069] Especially preferred electrodes of the present invention
comprise active compounds selected from one or more of:
LiNi.sub.0.5-xMn.sub.0.5-xCu.sub.xTi.sub.xO.sub.2;
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2,
[0070] LiNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2; [0071]
LiNi.sub.0.33Mn.sub.0.33Cu.sub.0.167Ti.sub.0.167O.sub.2; [0072]
LiNi.sub.0.5-xMn.sub.0.5-xCa.sub.xTi.sub.xO.sub.2; [0073]
LiNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2; [0074]
LiNi.sub.0.5-xMn.sub.0.5-xMg.sub.xTi.sub.xO.sub.2; [0075]
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2; [0076]
LiNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2; [0077]
LiNi.sub.0.5-xTi.sub.0.5-xMg.sub.xMn.sub.xO.sub.2; and [0078]
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167Mg.sub.0.1583Mn.sub.0.2083O.sub.2.
[0079] The electrodes according to the present invention are
suitable for use in many different applications, for example energy
storage devices, rechargeable batteries, electrochemical devices
and electrochromic devices.
[0080] Advantageously, the electrodes according to the invention
are used in conjunction with a counter electrode and one or more
electrolyte materials. The electrolyte materials may be any
conventional or known materials and may comprise either aqueous
electrolyte(s) or non-aqueous electrolyte(s) or mixtures
thereof.
[0081] In a third aspect, the present invention provides an energy
storage device that utilises an electrode comprising the active
materials described above, and particularly an energy storage
device for use as one or more of the following: an alkali metal ion
cell; an alkali metal-metal cell; a non-aqueous electrolyte alkali
metal ion cell; or an aqueous electrolyte alkali metal ion cell,
wherein the alkali metal comprises lithium alone or a mixture of
lithium and one or more other alkali metals wherein lithium is the
major alkali metal constituent in the mixture.
[0082] The novel compounds of the present invention may be prepared
using any known and/or convenient method. For example, the
precursor materials may be heated in a furnace so as to facilitate
a solid state reaction process.
[0083] A fourth aspect of the present invention provides a
particularly advantageous method for the preparation of the
compounds described above comprising the steps of:
a) mixing the starting materials together, preferably intimately
mixing the starting materials together and further preferably
pressing the mixed starting materials into a pellet; b) heating the
mixed starting materials in a furnace at a temperature of between
400.degree. C. and 1500.degree. C., preferably a temperature of
between 500.degree. C. and 1200.degree. C., for between 2 and 20
hours; and c) allowing the reaction product to cool.
[0084] Preferably the reaction is conducted under an atmosphere of
ambient air, and alternatively under an inert gas.
[0085] It is also possible to prepare lithium-ion materials from
the sodium-ion derivatives by converting the sodium-ion materials
into lithium-ion materials using an ion exchange process.
[0086] Typical ways to achieve Na to Li ion exchange include:
1. Mixing the sodium-ion rich material with an excess of a
lithium-ion material e.g. LiNO.sub.3, heating to above the melting
point of LiNO.sub.3 (264.degree. C.), cooling and then washing to
remove the excess LiNO.sub.3 and side-reaction products. 2.
Treating the Na-ion rich material with an aqueous solution of
lithium salts, for example 1M LiCl in water; and 3. Treating the
Na-ion rich material with a non-aqueous solution of lithium salts,
for example LiBr in one or more aliphatic alcohols such as hexanol,
propanol etc.
BRIEF DESCRIPTION OF THE DRAWINGS
[0087] The present invention will now be described with reference
to the following figures in which:
[0088] FIG. 1A is an XRD of
NaNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (lower
profile) and LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2
(upper profile) prepared according to Example 1;
[0089] FIG. 1B shows the Electrode Voltage (V vs Li) versus
Cumulative Cathode Specific Capacity (mAh/g) for
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 prepared
according to Example 1;
[0090] FIG. 1C shows the first cycle Differential Capacity
(mAh/g/V) versus Electrode Voltage (v vs Li) for
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 prepared
according to Example 1;
[0091] FIG. 2A is an XRD of
NaNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2 (lower profile)
and LiNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2 (upper
profile) prepared according to Example 2;
[0092] FIG. 2B shows the Electrode Voltage (V vs Li) versus
Cumulative Cathode Specific Capacity (mAh/g) for
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.1Ti.sub.0.1O.sub.2 prepared
according to Example 2;
[0093] FIG. 2C shows the first cycle Differential Capacity
(mAh/g/V) versus Electrode Voltage (v vs Li) for
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.1Ti.sub.0.1O.sub.2 prepared
according to Example 2;
[0094] FIG. 3A is an XRD of
NaNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (lower profile)
and LiNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (upper
profile) prepared according to Example 3;
[0095] FIG. 3B shows the Electrode Voltage (V vs Li) versus
Cumulative Cathode Specific Capacity (mAh/g) for
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.1Ti.sub.0.1O.sub.2 prepared
according to Example 3;
[0096] FIG. 3C shows the first cycle Differential Capacity
(mAh/g/V) versus Electrode Voltage (v vs Li) for
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.1Ti.sub.0.1O.sub.2 prepared
according to Example 3;
[0097] FIG. 4A is an XRD of
NaNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 (lower
profile) and LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2
(upper profile) prepared according to Example 4;
[0098] FIG. 4B shows the Electrode Voltage (V vs Li) versus
Cumulative Cathode Specific Capacity (mAh/g) for
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 prepared
according to Example 4;
[0099] FIG. 4C shows the first cycle Differential Capacity
(mAh/g/V) versus Electrode Voltage (v vs Li) for
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 prepared
according to Example 4;
[0100] FIG. 5A is an XRD of
NaNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2 (lower
profile) and
LiNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2 (upper
profile) prepared according to Example 5
[0101] FIG. 5B shows the Electrode Voltage (V vs Li) versus
Cumulative Cathode Specific Capacity (mAh/g) for
LiNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2 prepared
according to Example 5;
[0102] FIG. 5C shows the first cycle Differential Capacity
(mAh/g/V) versus Electrode Voltage (v vs Li) for
LiNi.sub.0.33Mn.sub.0.33Mg.sub.0.167Ti.sub.0.167O.sub.2 prepared
according to Example 5; and
[0103] FIG. 6A is an XRD of
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167Mg.sub.0.1583Mn.sub.0.2083O.sub.2
prepared according to Example 6.
DETAILED DESCRIPTION
[0104] The materials according to the present invention are
prepared using the following generic method:
Generic Synthesis Method:
[0105] Stoichiometric amounts of the precursor materials are
intimately mixed together and pressed into a pellet. The resulting
mixture is then heated in a tube furnace or a chamber furnace using
either an ambient air atmosphere, or a flowing inert atmosphere
(e.g. argon or nitrogen), at a furnace temperature of between
400.degree. C. and 1500.degree. C. until reaction product forms;
for some materials a single heating step is used and for others
more than one heating step is used. When cool, the reaction product
is removed from the furnace and ground into a powder.
Product Analysis Using XRD
[0106] All of the product materials were analysed by X-ray
diffraction techniques using a Siemens D5000 powder diffractometer
to confirm that the desired target materials had been prepared, to
establish the phase purity of the product material and to determine
the types of impurities present. From this information it is
possible to determine the unit cell lattice parameters.
[0107] The operating conditions used to obtain the XRD spectra
illustrated herein, are as follows:
Slits sizes: 1 mm, 1 mm, 0.1 mm
Range: 2.theta.=5 .degree.-60 .degree.
X-ray Wavelength=1.5418 .ANG. (Angstoms) (Cu K.alpha.)
[0108] Speed: 0.5 seconds/step
Increment: 0.015.degree. for FIGS. 1A, 2A, 3A, 4A and 5A and
0.025.degree. for FIG. 6A
[0109] Electrochemical Results
[0110] The target materials were tested using a lithium metal anode
test cell. It is also possible to test using a Li-ion cell with a
graphite anode. Cells may be made using the following
procedures:
Generic Procedure to Make a Lithium Metal Electrochemical Test
Cell
[0111] The positive electrode is prepared by solvent-casting a
slurry of the active material, conductive carbon, binder and
solvent. The conductive carbon used is Super P (Timcal). PVdF
co-polymer (e.g. Kynar Flex 2801, Elf Atochem Inc.) is used as the
binder, and acetone is employed as the solvent. The slurry is then
cast onto glass and a free-standing electrode film is formed as the
solvent evaporates. The electrode is then dried further at about
80.degree. C. The electrode film contains the following components,
expressed in percent by weight: 80% active material, 8% Super P
carbon, and 12% Kynar 2801 binder. Optionally, an aluminium current
collector may be used to contact the positive electrode. Metallic
lithium on a copper current collector may be employed as the
negative electrode. The electrolyte comprises one of the following:
(i) a 1 M solution of LiPF.sub.6 in ethylene carbonate (EC) and
dimethyl carbonate (DMC) in a weight ratio of 1:1; (ii) a 1 M
solution of LiPF.sub.6 in ethylene carbonate (EC) and diethyl
carbonate (DEC) in a weight ratio of 1:1; or (iii) a 1 M solution
of LiPF.sub.6 in propylene carbonate (PC) A glass fibre separator
(Whatman, GF/A) or a porous polypropylene separator (e.g. Celgard
2400) wetted by the electrolyte is interposed between the positive
and negative electrodes.
Generic Procedure to Make a Graphite Li-Ion Cell
[0112] The positive electrode is prepared by solvent-casting a
slurry of the active material, conductive carbon, binder and
solvent. The conductive carbon used is Super P (Timcal). PVdF
co-polymer (e.g. Kynar Flex 2801, Elf Atochem Inc.) is used as the
binder, and acetone is employed as the solvent. The slurry is then
cast onto glass and a free-standing electrode film is formed as the
solvent evaporates. The electrode is then dried further at about
80.degree. C. The electrode film contains the following components,
expressed in percent by weight: 80% active material, 8% Super P
carbon, and 12% Kynar 2801 binder. Optionally, an aluminium current
collector may be used to contact the positive electrode.
[0113] The negative electrode is prepared by solvent-casting a
slurry of the graphite active material (Crystalline Graphite,
supplied by Conoco Inc.), conductive carbon, binder and solvent.
The conductive carbon used is Super P (Timcal). PVdF co-polymer
(e.g. Kynar Flex 2801, Elf Atochem Inc.) is used as the binder, and
acetone is employed as the solvent. The slurry is then cast onto
glass and a free-standing electrode film is formed as the solvent
evaporates. The electrode is then dried further at about 80.degree.
C. The electrode film contains the following components, expressed
in percent by weight: 92% active material, 2% Super P carbon, and
6% Kynar 2801 binder. Optionally, a copper current collector may be
used to contact the negative electrode.
Cell Testing
[0114] The cells are tested as follows, using Constant Current
Cycling techniques.
[0115] The cell is cycled at a given current density between
pre-set voltage limits. A commercial battery cycler from Maccor
Inc. (Tulsa, Okla., USA) is used. On charge, lithium ions are
extracted from the cathode active material. During discharge,
lithium ions are re-inserted into the cathode active material.
[0116] The above methods were used in the following Examples 1 to 6
to prepare active materials according to the present invention.
Example 1
Target Phase
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (X0453)
STEP 1: The Preparation of
NaNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (X0421a)
Precursor Mix:
Na.sub.2CO.sub.3,
NiCO.sub.3,
MnO.sub.2
CuO
TiO.sub.2
Furnace Conditions:
[0117] 1) Air/900.degree. C., dwell time of 8 hours 2)
Air/900.degree. C., dwell time of 8 hours.
STEP 2: Ion Exchange Reaction to Produce
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (X0453)
Precursor Mix:
[0118] NaNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2
(X0421a), LiNO.sub.3 (15.times.molar excess)
Furnace Conditions:
[0119] 300.degree. C., air, dwell time of 2 hours Washed in
deionised water, to remove LiNO.sub.3 and NaNO.sub.3 (formed during
ion exchange process) and dried under vacuum
Analysis of Product
[0120] FIG. 1(A) shows the XRD obtained for the target material
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2, (upper
profile) and the precursor material
NaNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (lower
profile). The presence and high purity of the lithium-containing
target material is confirmed by the absence of any Na-containing
phase being seen in the upper profile, and by the fact that the
lithium-containing target material phase exhibits a substantial
increase in peak angles. This suggests a smaller unit cell than for
the precursor material and is consistent with the replacement of Na
with Li.
Electrochemical Results:
[0121] The data shown in FIG. 1(B) (Electrode Voltage (V vs. Li)
versus Cumulative Cathode Specific Capacity (mAh/g)) are derived
from the constant current cycling data for the
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (Sample
X0453) active material in a metallic lithium half-cell. The
electrolyte used was a 1.0 M solution of LiPF.sub.6 in ethylene
carbonate/diethyl carbonate. The constant current data were
collected at an approximate current density of 0.20 mA/cm.sup.2
between voltage limits of 3.00 and 4.30 V vs. Li. The testing was
carried out at 25.degree. C. During the cell charging process,
lithium ions are extracted from the cathode active material. During
the subsequent discharge process, lithium ions are re-inserted into
the cathode active material. The first charge process corresponds
to a cathode specific capacity of 151 mAh/g. The first discharge
process corresponds to a cathode specific capacity of 97 mAh/g.
These data demonstrate the reversibility of the lithium ion
insertion reactions in the
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 active
material.
[0122] FIG. 1(C) shows the first cycle differential capacity
profile (Differential Capacity (mAh/g/V) versus Electrode Voltage
(V vs. Li)] for the
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 (Sample
X0453) derived from the constant current cycling data shown in FIG.
1(B). Differential capacity data have been shown to allow
characterization of the reaction reversibility, order-disorder
phenomenon and structural phase changes within the ion insertion
system.
[0123] The data presented in FIG. 1(C) for the
LiNi.sub.0.45Mn.sub.0.45Cu.sub.0.05Ti.sub.0.05O.sub.2 cathode
confirm the reversible lithium-ion insertion behaviour as
characterized by the generally symmetrical nature of the
differential capacity peaks during cell charge and discharge.
Example 2
Target Phase
LiNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2 (X0454)
STEP 1: The Preparation of
NaNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2(X0423b)
Precursor Mix:
TiO.sub.2
Na.sub.2CO.sub.3,
NiCO.sub.3,
MnO.sub.2
CaCO.sub.3
Furnace Conditions:
[0124] 1) Air/900.degree. C., dwell time of 8 hours 2)
Air/900.degree. C., dwell time of 8 hours. 3) Air/950.degree. C.,
dwell time of 8 hours
STEP 2: Ion Exchange Reaction to Produce
LiNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2 (X0454)
Precursor Mix: --
[0125] NaNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2 (X0423b),
LiNO.sub.3 (15.times.molar excess)
Furnace Conditions:
[0126] 300.degree. C., air, dwell time of 2 hours Washed in
deionised water, to remove LiNO.sub.3 and NaNO.sub.3 (formed during
ion exchange process) and dried under vacuum
Analysis of Product
[0127] FIG. 2(A) shows the XRD obtained for the target material
LiNi.sub.0.4Mn.sub.0.4Ca.sub.0.1Ti.sub.0.1O.sub.2, (upper profile)
and the precursor material
NaNi.sub.0.40Mn.sub.0.40Ca.sub.0.1Ti.sub.0.1O.sub.2 (lower
profile). The presence and high purity of the lithium-containing
target material is confirmed by the absence of any Na-containing
phase being seen in the upper profile, and by the fact that the
lithium-containing target material phase exhibits a substantial
increase in peak angles. This suggests a smaller unit cell than for
the precursor material and is consistent with the replacement of Na
with Li.
Electrochemical Results:
[0128] The data shown in FIG. 2(B) (Electrode Voltage (V vs. Li)
versus Cumulative Cathode Specific Capacity (mAh/g)) are derived
from the constant current cycling data for the
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.10Ti.sub.0.10O.sub.2 (Sample
X0454) active material in a metallic lithium half-cell. The
electrolyte used was a 1.0 M solution of LiPF.sub.6 in ethylene
carbonate/diethyl carbonate. The constant current data were
collected at an approximate current density of 0.20 mA/cm.sup.2
between voltage limits of 3.00 and 4.30 V vs. Li. The testing was
carried out at 25.degree. C. During the cell charging process,
lithium ions are extracted from the cathode active material. During
the subsequent discharge process, lithium ions are re-inserted into
the cathode active material. The first charge process corresponds
to a cathode specific capacity of 135 mAh/g. The first discharge
process corresponds to a cathode specific capacity of 108 mAh/g.
These data demonstrate the reversibility of the lithium ion
insertion reactions in the
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.10Ti.sub.0.10O.sub.2 active
material.
[0129] FIG. 2(C) shows the first cycle differential capacity
profile (Differential Capacity [mAh/g/V versus Electrode Voltage (V
vs. Li)] for the
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.10Ti.sub.0.10O.sub.2 (Sample
X0454) derived from the constant current cycling data shown in FIG.
2(B). Differential capacity data have been shown to allow
characterization of the reaction reversibility, order-disorder
phenomenon and structural phase changes within the ion insertion
system.
[0130] The data presented in FIG. 2(C) for the
LiNi.sub.0.40Mn.sub.0.40Ca.sub.0.10Ti.sub.0.10O.sub.2 cathode
confirm the reversible lithium-ion insertion behaviour as
characterized by the generally symmetrical nature of the
differential capacity peaks during cell charge and discharge.
Example 3
Target Phase
LiNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (X0455)
STEP 1: The Preparation of
NaNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (X0425)
Precursor Mix:
Na.sub.2CO.sub.3,
NiCO.sub.3,
MnO.sub.2
CuO
TiO.sub.2
Furnace Conditions:
[0131] 1) Air/900.degree. C., dwell time of 8 hours 2)
Air/900.degree. C., dwell time of 8 hours
STEP 2: Ion Exchange Reaction to Prepare
LiNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (X0455)
Precursor Mix:
[0132] NaNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (X0425),
LiNO.sub.3 (15.times.molar excess)
Furnace Conditions:
[0133] 300.degree. C., air, dwell time of 2 hours Washed in
deionised water, to remove LiNO.sub.3 and NaNO.sub.3 (formed during
ion exchange process) and dried under vacuum
Analysis of Product
[0134] FIG. 3(A) shows the XRD obtained for the target material
LiNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2, (upper profile)
and the precursor material
NaNi.sub.0.4Mn.sub.0.4Cu.sub.0.1Ti.sub.0.1O.sub.2 (lower profile).
The presence and high purity of the lithium-containing target
material is confirmed by the absence of any Na-containing phase
being seen in the upper profile, and by the fact that the
lithium-containing target material phase exhibits a substantial
increase in peak angles. This suggests a smaller unit cell than for
the precursor material and is consistent with the replacement of Na
with Li.
Electrochemical Results:
[0135] The data shown in FIG. 3(B) (Electrode Voltage (V vs. L i)
versus Cumulative Cathode Specific Capacity (mAh/g)) are derived
from the constant current cycling data for the
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.10Ti.sub.0.10O.sub.2 (Sample
X0455) active material in a metallic lithium half-cell. The
electrolyte used was a 1.0 M solution of LiPF.sub.6 in ethylene
carbonate/diethyl carbonate. The constant current data were
collected at an approximate current density of 0.20 mA/cm.sup.2
between voltage limits of 3.00 and 4.30 V vs. Li. The testing was
carried out at 25.degree. C. During the cell charging process,
lithium ions are extracted from the cathode active material. During
the subsequent discharge process, lithium ions are re-inserted into
the cathode active material. The first charge process corresponds
to a cathode specific capacity of 139 mAh/g. The first discharge
process corresponds to a cathode specific capacity of 90 mAh/g.
These data demonstrate the reversibility of the lithium ion
insertion reactions in the
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.10Ti.sub.0.10O.sub.2 active
material.
[0136] FIG. 3(C) shows the first cycle differential capacity
profile (Differential Capacity [mAh/g/V versus Electrode Voltage (V
vs. Li)] for the
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.10Ti.sub.0.10O.sub.2 (Sample
X0455) derived from the constant current cycling data shown in FIG.
3(B). Differential capacity data have been shown to allow
characterization of the reaction reversibility, order-disorder
phenomenon and structural phase changes within the ion insertion
system.
[0137] The data presented in FIG. 3(C) for the
LiNi.sub.0.40Mn.sub.0.40Cu.sub.0.10Ti.sub.0.10O.sub.2 cathode
confirm the reversible lithium-ion insertion behaviour as
characterized by the generally symmetrical nature of the
differential capacity peaks during cell charge and discharge.
Example 4
Target Phase
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 (X0654)
STEP 1: Preparation of
NaNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 (X0472a)
Precursor Mix:
Al(OH).sub.3
Na.sub.2CO.sub.3
NiCO.sub.3
Mg(OH).sub.2
MnO.sub.2
TiO.sub.2
Furnace Conditions:
[0138] 1) Air/800.degree. C., dwell time of 8 hours 2)
Air/900.degree. C., dwell time of 8 hours.
STEP 2: Ion Exchange Reaction to Produce
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 (X0654)
Precursor Mix: --
[0139] NaNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2
(X0472a), LiNO.sub.3 (15.times.molar excess)
Furnace Conditions:
[0140] 300.degree. C., air, dwell time of 2 hours Washed in
deionised water, to remove LiNO.sub.3 and NaNO.sub.3 (formed during
ion exchange process) and dried under vacuum
Analysis of Product
[0141] FIG. 4(A) shows the XRD obtained for the target material
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2, (upper
profile) and the precursor material
NaNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.05O.sub.2 (lower
profile). The presence and high purity of the lithium-containing
target material is confirmed by the absence of any Na-containing
phase being seen in the upper profile, and by the fact that the
lithium-containing target material phase exhibits a substantial
increase in peak angles. This suggests a smaller unit cell than for
the precursor material and is consistent with the replacement of Na
with Li.
Electrochemical Results:
[0142] The data shown in FIG. 4(B) (Electrode Voltage (V vs. Li)
versus Cumulative Cathode Specific Capacity (mAh/g)) are derived
from the constant current cycling data for the
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.10O.sub.2 (Sample
X0654) active material in a metallic lithium half-cell. The
electrolyte used was a 1.0 M solution of LiPF.sub.6 in ethylene
carbonate/diethyl carbonate. The constant current data were
collected at an approximate current density of 0.20 mA/cm.sup.2
between voltage limits of 3.00 and 4.20 V vs. Li. The testing was
carried out at 25.degree. C. During the cell charging process,
lithium ions are extracted from the cathode active material. During
the subsequent discharge process, lithium ions are re-inserted into
the cathode active material. The first charge process corresponds
to a cathode specific capacity of 193 mAh/g. The first discharge
process corresponds to a cathode specific capacity of 115 mAh/g.
These data demonstrate the reversibility of the lithium ion
insertion reactions in the
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.10O.sub.2 active
material.
[0143] FIG. 4(C) shows the first cycle differential capacity
profile (Differential Capacity [mAh/g/V versus Electrode Voltage (V
vs. Li)] for the
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.10O.sub.2 (Sample
X0654) derived from the constant current cycling data shown in FIG.
4(B). Differential capacity data have been shown to allow
characterization of the reaction reversibility, order-disorder
phenomenon and structural phase changes within the ion insertion
system.
[0144] The data presented in FIG. 4(C) for the
LiNi.sub.0.45Mn.sub.0.45Mg.sub.0.05Ti.sub.0.10O.sub.2 cathode
confirm the reversible lithium-ion insertion behaviour as
characterized by the generally symmetrical nature of the
differential capacity peaks during cell charge and discharge.
Example 5
Target Phase
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2
(X0655)
STEP 1: Preparation of
NaNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2
(X0628)
Precursor Mix:
TiO.sub.2Na.sub.2CO.sub.3
NiCO.sub.3
MnO.sub.2
Mg(OH).sub.2
Furnace Conditions:
[0145] 1) Air/900.degree. C., dwell time of 8 hours 2)
Air/900.degree. C., dwell time of 8 hours.
STEP 2: Ion Exchange Reaction to Produce
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2
(X0655)
Precursor Mix:
[0146] NaNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2
(X0628), LiNO.sub.3 (15.times.molar excess)
Furnace Conditions:
[0147] 300.degree. C., air, dwell time of 2 hours Washed in
deionised water, to remove LiNO.sub.3 and NaNO.sub.3 (formed during
ion exchange process) and dried under vacuum
Analysis of Product
[0148] FIG. 5(A) shows the XRD obtained for the target material
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 (X0655),
(upper profile) and the precursor material
NaNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 (lower
profile). The presence and high purity of the lithium-containing
target material is confirmed by the absence of any Na-containing
phase being seen in the upper profile, and by the fact that the
lithium-containing target material phase exhibits a substantial
increase in peak angles. This suggests a smaller unit cell than for
the precursor material and is consistent with the replacement of Na
with Li.
Electrochemical Results:
[0149] The data shown in FIG. 5(B) (Electrode Voltage (V vs. Li)
versus Cumulative Cathode Specific Capacity (mAh/g)) are derived
from the constant current cycling data for the
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 (Sample
X0655) active material in a metallic lithium half-cell. The
electrolyte used was a 1.0 M solution of LiPF.sub.6 in ethylene
carbonate/diethyl carbonate. The constant current data were
collected at an approximate current density of 0.20 mA/cm.sup.2
between voltage limits of 3.00 and 4.20 V vs. Li. The testing was
carried out at 25.degree. C. During the cell charging process,
lithium ions are extracted from the cathode active material. During
the subsequent discharge process, lithium ions are re-inserted into
the cathode active material. The first charge process corresponds
to a cathode specific capacity of 132 mAh/g. The first discharge
process corresponds to a cathode specific capacity of 110 mAh/g.
These data demonstrate the reversibility of the lithium ion
insertion reactions in the
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 active
material.
[0150] FIG. 5(C) shows the first cycle differential capacity
profile (Differential Capacity [mAh/g/V versus Electrode Voltage (V
vs. Li)] for the
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 (Sample
X0655) derived from the constant current cycling data shown in FIG.
5(B). Differential capacity data have been shown to allow
characterization of the reaction reversibility, order-disorder
phenomenon and structural phase changes within the ion insertion
system.
[0151] The data presented in FIG. 5(C) for the
LiNi.sub.0.333Mn.sub.0.333Mg.sub.0.167Ti.sub.0.167O.sub.2 cathode
confirm the reversible lithium-ion insertion behaviour as
characterized by the generally symmetrical nature of the
differential capacity peaks during cell charge and discharge.
Example 6
Target Material
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167Mg.sub.0.1583Mn.sub.0.2083O.sub.2
(X1388c)
Precursor Mix:
0.475 Li.sub.2CO.sub.3
0.3167 NiCO.sub.3
0.3167 TiO.sub.2
0.2083 MnO.sub.2
0.1583 Mg(OH).sub.2
Mixing Solvent:
Acetone
Furnace Conditions: --
[0152] 700.degree. C. in air, dwell time of 10 hours 800.degree. C.
in air, dwell time of 20 hours 900.degree. C. in air, dwell time of
8 hours 1000.degree. C. in air, dwell time of 8 hours (sample
reground and repelletised between each firing)
Analysis of Product
[0153] FIG. 6(A) shows the XRD for the target product
Li.sub.0.95Ni.sub.0.3167Ti.sub.0.3167Mg.sub.0.1583Mn.sub.0.2083O.sub.2
* * * * *