Lithiated manganese oxide

Details Lithiated manganese oxide Lithiated manganese oxide

1999-05-14

2001-03-27

Dunn, Tom (Department: 1754)

Chemistry of inorganic compounds

Oxygen or compound thereof

Metal containing

C423S179500, C423S181000, C423S605000, C423S641000, C429S224000, C429S231950

Reexamination Certificate

active

06207129

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a method of making lithiated manganese oxide which is particularly useful in the manufacture of lithium/manganese batteries or other applications involving lithium intercalation or deintercalation. More particularly, this invention is directed to making LiMn
2
O
4
from a manganese dioxide which has sodium and/or potassium ions, exchanging the sodium and/or potassium ions for lithium ions in an ion exchange reaction and where the LiMn
2
O
4
has an x-ray pattern recognized as particularly useful in the manufacture of batteries.
BACKGROUND OF THE INVENTION
Manganese dioxide is a known material for use as a cathodic material in batteries. It also is known that it is not particularly suitable for rechargeable batteries. Apparently irreversible structural changes occur in manganese dioxide during discharge which do not permit recharging.
Lithiated manganese oxide made from manganese dioxide (MnO
2
) has been investigated for use in rechargeable batteries. The method of making the lithiated manganese oxide and the manganese dioxide starting material appears to materially affect the effectiveness of the lithiated manganese oxide used in rechargeable batteries. U.S. Pat. Nos. 4,312,930 and 4,246,253 to Hunter describe a lithiated manganese oxide which Hunter says has a particularly effective utility for rechargeable batteries. Each of these Hunter patents is incorporated herein as if fully rewritten.
Making lithiated manganese compounds is not necessarily new. Monchilov and Manev describe making lithiated manganese compounds (see Journal of Power Sources, 41 (1993) 305-314 and Log Batteries, Battery Mater., Vol. 14 (1995), respectively), but do not describe making such compounds from relatively impure compounds which have a high sodium and/or potassium content and making relatively pure lithiated manganese compounds by removing the sodium and/or potassium and replacing those alkali metals with lithium to make a pure lithiated manganese compound.
U.S. Pat. No. 5,759,510 to Pillai and copending application Serial No. PCT/US97/17081, filed Sep. 30, 1997, (which is a continuation-in-part application from the application which matured into U.S. Pat. No. 5,759,510) describe making lithiated manganese oxide from manganese dioxide. When compared to the process described herein, the process described in these copending applications are more complex, require higher temperatures, do not use an ion exchange reaction, and hence require more severe conditions in making an initially calcined product which is thereafter calcined. As a result these processes are more likely to generate more impurities and are more energy intensive.
An object of this invention is to provide a process for making lithiated manganese oxide.
Another object of this invention is to use chemically made manganese dioxide having sodium and/or potassium ions in making the lithiated manganese oxide by the process of the invention.
Yet another object of this invention is to make a pure form of lithiated manganese oxide from the reduction of a sodium and/or potassium permanganate or manganate and controlling the ratio of sodium and/or potassium ions in the amorphous manganese oxide which results from the reduction of the permanganate or manganate such that the lithiated manganese oxide has a utility that is particularly effective for a cathodic material for rechargeable batteries.
Yet another object of the invention is to make a lithiated manganese oxide by a process which has few steps, has a low manganese and lithium loss and is energy efficient.
Further objects and advantages of the invention will be found by reference to the following specification.
As used herein, LiMn
2
O
4
means a lithiated manganese oxide with the general formula Li
1+x
Mn
2−y
O
4
where x is greater than about −0.11 and less than about +0.33, and y is equal to about 0 to about 0.33.
As used herein, “amorphous manganese dioxide” means a manganese dioxide which does not have a substantially identifiable crystal structure as determined by x-ray diffractometry.
As used herein, “delta manganese dioxide” means a manganese dioxide which does not have a single crystal structure which dominates to provide a manganese dioxide with at least one identifiable crystal structure. Delta manganese dioxide is often described as having the following general formula M
2
O.4MnO
2
where M is an alkali metal cation.
As used herein, “reducing permanganate” means taking the oxidation state of manganese (VII) to manganese (III or IV).
As used herein, “substantially all Mn IV” means at least about 90 weight percent Mn IV and not more than about 10 weight percent Mn III.
As used herein, “defect spinel” is all material within the general formula Li
1+x
Mn
2−y
O
4
where x is greater than about −0.11 and less than about +0.33 and y is about 0 to about 33, but not LiMn
2
O
4
(where x & y are 0). A specific defect spinel which has utility is where the Li to Mn ion molar ratio is about 0.5.
Another type of defect spinel which has utility is a stoichiometric spinel where the oxidation state of the manganese varies from about 3.5 to 4.0. In the former example of a defect spinel, the Li to Mn ion molar ratio is controlled by how much sodium and/or potassium ions are in the MnO
2
and pH control of the reaction (through the use of LiOH) to get the spinel. To raise the Li to Mn ratio to about 0.6, the pH should be raised. The nature of stoichiometric spinel may be controlled by reaction temperature. Increase the reaction temperature to get the spinel and decrease the oxidation state of the Mn.
SUMMARY OF THE INVENTION
The process of the invention provides a high purity LiMn
2
O
4
from chemically made amorphous MnO
2
that has sodium and potassium impurities therein. The amount of lithium in the resulting lithiated manganese oxide is controlled through the ratio of sodium and/or potassium ions in the amorphous manganese dioxide. This is because the sodium and/or potassium ions ultimately are exchanged or replaced with lithium ions via an ion exchange reaction. It is these lithium ions in the lithiated manganese oxide which provide the lithiated manganese oxide an especially effective utility for use as a cathodic material in rechargeable batteries. The invention is particularly useful and nonobvious because (1) it utilizes as a starting material a relatively inexpensive chemically made manganese dioxide with alkali metal impurities in it, (2) removes the unwanted alkali metals, such as sodium and potassium, with less manganese loss than previously known processes, (3) replaces the sodium and/or potassium with lithium in less steps than previously known processes, (4) lowers or mitigates lithium loss relative to previously known processes, (5) lowers energy consumption relative to previously known processes to make a pure spinel LiMn
2
O
4
material because the method of the invention permits lower temperatures in making an ion replaced product which when calcined provides the lithiated manganese oxide, (6) lowers the amount of impurities from manganese because by running an ion exchange reaction at relatively low temperatures, manganese impurities generated by high temperatures or harsh conditions to replace sodium and/or potassium ions with lithium ions are not created, (7) exhibits higher degrees of control over the physical properties of the material than previously known processes, and (8) provides a method of preparing a series of defect and stoichiometric spinels. It is the spinel material which is especially useful for batteries. Moreover, the invention has the ability to remove sodium and/or potassium to an amount of at least not more than about 0.001 moles of sodium and potassium together, per mole of manganese, in the lithiated manganese compound (not more than about 0.001 moles of sodium and potassium, per mole of manganese, are left in the lithiated manganese compound).
The process of the invention utilizes amorphous manganese dioxide which has a ratio of sodium and/or potassium ions t

Affiliated with

Also associated with

Rating

Lithiated manganese oxide does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Lithiated manganese oxide, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Lithiated manganese oxide will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2475608