JPH04240117A - Manganese oxide compound - Google Patents

Abstract

PURPOSE: To provide a method for producing a lithium manganese oxide compound suitable to be used as the electrode of an electrochemical cell and the cell to use the compound as a cathode.

CONSTITUTION: This invention relates to the lithium manganese oxide compound having the general formula, Li₂O.yMnO₂ [(y) presents a value larger than 5, all the Mn cations are practically tetravalent and this compound supplies an open circuit voltage lower than 3.50 V when coupled with lithium in by appropriate electrolyte in the electrochemical cell], the production of the said compound and the electrochemical cell using the said compound as the cathode are provided.

COPYRIGHT: (C)1992,JPO

Description

[Detailed description of the invention]

[0001] The present invention relates to an electrochemical cell (electr
Lithium manganese oxide compounds suitable for use as electrodes in chemical cells
m manganese oxide compound
d), a method for producing said compound and an electrochemical cell using said compound as cathode.

One aspect of the present invention is that the general formula, Li2
O.yMnO2 (where y has a value greater than 5, the Mn cations are substantially all tetravalent, and when combined with lithium by a suitable electrolyte in an electrochemical cell, this compound has a valence of 3.
open circuit voltage less than 50V
The object of the present invention is to provide a lithium manganese oxide compound which is a lithium manganese oxide compound which supplies a

"Substantially all tetravalent" means that the average valence of the manganese cations is at least +3.
．． 7 and usually more, eg 3.8-4.0.

[0004] The present compound has as a separate phase within it:
Lithium manganese oxide component with spinel-type structure
nt ) and the manganese oxide component (manga
(nese oxide component). Instead, it is essentially single-phase (single-p
It may have a spinel type structure.

Preferably, the compound has a voltage of less than 3.40 V, more preferably 3.40 V, when combined with lithium in said battery.
．． Those that provide an open circuit voltage of less than 35V are preferred.

[0006] Stoichiometric
c) The spinel compound has the general formula A[B2]X4
It has a structure represented by
on) and face-share (face-share).
ing) and edge-sharing tetrahedra and octahedra
form an array of negatively charged anions consisting of hedra). General formula A [B2]
In X4, the A atom is a tetrahedral site (tetrahed
The B atom is a cation of an octahedral site (octahedra-site). That is, the A and B cations occupy tetrahedral and octahedral positions, respectively. In an ideal spinel structure, the unit cell
) is at the center (

[0007]

[Math 1]

), and the closest-packed anion is located at position 32e in space group Fd3m. Each unit cell consists of 64 tetrahedral interstices located at three crystallographically non-equivalent positions 8a, 8b and 48f.
, and 32 octahedral lattice gaps located at crystallographically non-equivalent positions of 16c and 16d. A [ B
2 ] In the spinel form of X4, the A cation is
Located in the lattice gap of the tetrahedron of 8a, the B cation is
It belongs to the lattice gap of the 16d octahedron. Thus, there are 56 empty tetrahedral sites and 16 empty octahedral sites per cubic unit cell.

Therefore, the B cation of the backbone structure of the host of [B2]
The anion may be considered to be located at position 32e of the spinel structure. The tetrahedron defined by the positions of 8a, 8b and 48f and the octahedron defined by 16c of the spinel structure are thus [ B2 ]
The interstitial space of the n-skeletal structure
al space).

For example, the lithium manganese oxide compound Li[Mn2]O4 having a spinel structure can be used in primary batteries and rechargeable batteries (cells and
It is known to use lithium as the cathode of batteries (along with lithium, which is the active material of the anode). Li[Mn2]O4 is generally heated at 700℃
Manganese oxide is produced by reacting lithium salts with manganese oxide at temperatures above . In this structure, half M
The n cation is quadrivalent, and the other half is trivalent. 1M
λ-MnO2 using an inorganic acid such as sulfuric acid or hydrochloric acid
The manganese oxide phase, known as
) Lithium can be removed from the structure of Li[Mn2]O4 by oxidation of trivalent manganese cations to form . And, the λ-MnO2 is expressed as □1.0 [Mn2] O4 (
Hunter, U.S. Patent 4,246,25
3) has a defective spinel-type structure that can be expressed as Thus, all Mn cations in λ-MnO2 are tetravalent.

Another example of a lithium manganese oxide compound having a spinel structure is Li4 Mn5 O
12 are mentioned. This compound has a more complex cation distribution expressed in spinel type notation as Li[ Li1/3 Mn5/3 ] O4. In this compound, all Mn cations are tetravalent, as in λ-MnO2.

Using the formula Li2 O.yMnO2, the stoichiometrically ideal and defect-free compound Li4 Mn5
It will be appreciated that O12 can be represented as Li2O.yMnO2 with y=2.5. and the defective and non-stoichiometric spinel-type compound λ-MnO.
2 can be expressed as Li2O.yMnO2 where y is undefined (that is, the concentration of Li2O is zero). The present invention relates to compounds of the formula Li2O.yMnO2 as such, where y is greater than 5 and the concentration of Li2O is greater than 0. The spinel-type compounds of the present invention are defective, non-stoichiometric spinel-type compounds; therefore, the expression "spinel-type compounds" covers defective, non-stoichiometric spinel-type compounds.

As described above, the compound of the present invention is not a stoichiometric spinel type compound, but defects are created by changing the amount of Li ions in the A site. Compounds are synthesized with such defects by varying the amount of Mn ions in the backbone structure. Therefore, a Li2O.yMnO2 compound with y=5 can instead have x=0.
273, Li1-x [ Mn2-z with z = 0.182
] O4. Compounds of the invention in which y is greater than 5 are, on the one hand, 0.27 in spinel type notation.
3<x<1, 0<z<0.182 Li1-x [M
n2-z]O4.

In the present invention, the A site is partially occupied by Li cations, the B site is partially occupied by Mn cations, and the X anion is an O anion. In this way, the skeletal structure is negatively charged [
It has a Mn2-z □z ] O4 structure. However, □ represents a vacancy and is considered as part of the interstitial space, which is a part of the Li that can move due to diffusion during the electrochemical discharge and charge reactions, as shown below.
Used for cations.

The above-mentioned A[ B2 ] X4 structure is known as a normal spinel structure. However, an arrangement in which some B cations occupy tetrahedral sites normally occupied by A cations and some A cations occupy octahedral sites normally occupied by B cations It is possible that the cations are rearranged. If the portion of the B cation occupying the tetrahedral site is called λ, the value of λ is 0 in a normal spinel structure. If the value of λ is 0.5, the spinel structure is known as an inverse spinel structure represented by the general formula B[AB]X4. In compounds with a spinel structure, an intermediate value of λ is common, and the value of λ does not necessarily have to be constant in a particular compound.
Depending on the case, it is also possible to change it by heat treatment under appropriate conditions.

[0016] In this specification, "spinel type structure"
means a defective spinel structure, as well as a normal spinel structure, an inverted spinel structure, and 0<λ<0.
It also includes intermediate structures of 5.

[0017] Li2O・yMnO2 with 2.5≦y≦5
Single-phase compounds represented by are known, for example, Li2O.yM where y=2.5 and y=4, respectively.
Li4 Mn5 O12 and Li expressed as nO2
2 Mn4 O9 is known. These compounds,
The manufacture and use of the compound in batteries is described in British patent application GB 2,221,213A and South African patent 89/5273. However, using the techniques described therein, the applicant has determined that y is 5
It was not possible to obtain single spinel phases of larger Li2O.yMnO2, and when y is greater than 5, the Li2O.yMnO2 produced by these techniques is similar to γ-MnO2 and/or
Or, it was contaminated with an impurity phase thought to be Mn2O3.

The compounds of the present invention, as mentioned above, have manganese which can be replaced by up to 20% with other metal ions, especially transition metals such as cobalt; Doping with metal oxides (
doping) does not affect the properties of the compounds of the invention for use in electrochemical cells of the type described below. By using the substituted metal in place of a part of the manganese oxide reagent used in the method for producing the compound of the present invention as shown below,
This doping can be done. Thus, up to 20% of the manganese cations may be replaced by other metal cations in the compounds of the invention.

The lithium manganese oxide compounds of the present invention can be prepared by solid state reaction means by reacting a lithium manganese oxide reagent with a suitable manganese oxide at elevated temperatures.

[0020] Thus, another aspect of the present invention is that the formula Li2O.yMn where y is greater than 5 as defined above
A method of synthesizing the lithium manganese oxide product of the present invention of O2 is provided. That is, in this method, the ratio of lithium and manganese ions is ≧1:2.
5, a lithium manganese oxide reagent and a manganese oxide reagent are reacted, and the method further comprises thoroughly mixing the reagents together in finely divided form with a particle size of up to 250 μm, and in an oxidizing atmosphere containing oxygen at a temperature in the range of 150-450°C for at least 8 hours.

Essentially, the proportions of lithium manganese oxide and manganese oxide reagents are selected on a stoichiometric basis to obtain a preferred value of y in the product.

Preferably, the reagent has a particle size of at most 50 μm.
and has a specific surface area larger than 20 m2/g,
The temperature is 240-400°C, the heating time is 8-16 hours, and the oxidizing atmosphere is selected from oxygen, air and mixtures thereof.

The lithium manganese oxide reagent preferably has a spinel structure and has the formula Li2 of 2.5≦y≦4.
Manganese oxide reagents such as O.yMnO2 and manganese dioxide include λ-MnO2, electrolytically prepared manganese dioxide (EMD), and chemically prepared manganese dioxide (CMD). and mixtures thereof.

The manganese dioxide reagent is λ-MnO2
The heating may be carried out at a temperature of 240-400° C. to obtain a substantially single-phase product.

Alternatively, the manganese dioxide reagent is selected from electrolytically prepared manganese dioxide (EMD), chemically prepared manganese dioxide (CMD) and mixtures thereof, and the heating is performed at 350-400°C. It may be carried out at a temperature of 0.degree. C. to obtain a product consisting of a component having a manganese dioxide phase in addition to a component having a spinel-type phase.

Preferably, the lithium manganese dioxide reagent is of the formula Li2 O.yMnO2 and when the value of y is 2.5, the reagent is of the formula Li4 Mn5 O
It can be expressed as 12.

[0027] Manganese dioxide reagent and 2.5≦y≦
The Li2O・yMnO2 reagent in No. 4 does not need to be stoichiometric, and the valence of Mn in it does not need to be exactly +4, but can vary by +4 depending on the temperature of preparation of the reagent.
It may be smaller. Thus, the valence is 3-4, preferably 3.5-4, more preferably 4.
It is. When the valence of Mn is less than 4, the manganese dioxide reagent and Li2O.yMnO2 are oxygen deficient.

[0028] Li2O・yMnO2 with 2.5≦y≦4
The reagent is obtained by reacting a lithium salt with a manganese salt according to the method described in British Patent Application GB 2,221,213A and South African Patent No. 89/5273, and is preferably combined with the lithium salt used in the preparation of this reagent. Anhydrous manganese salt is best.

The reaction between the Li2 O.yMnO2 reagent and the manganese dioxide reagent is preferably carried out at a temperature of 240-400° C., for example, for 8 hours to 1 week, preferably for 8 to 18 hours, as described above. Generally, the higher the temperature, the shorter the time, and the lower the temperature, the longer the time. The heating temperature depends, in part, on the manganese dioxide reagent used. λ-M in the absence of lithium
Since nO2 converts to β-MnO2 at 270 °C, a heating temperature of 240-270 °C is convenient (although higher temperatures can be used), and electrolytically and/or chemically prepared manganese For dioxide, 37
Temperatures of 5-400°C are commonly used.

By changing the molar ratio between the Li2O.yMnO2 reagent and the manganese dioxide reagent,
The value of y for the Li2O.yMnO2 product varies from values greater than 5 to possible large values such that the proportion of Li2O is very small to a fraction of 1% or less. In this way, this method produces high quality Li2O where y is 5.
・yMnO2 (product is South African patent 89/527
3, but of enhanced purity with substantially single-phase properties, and this method has been used by the applicant to produce the Li2O.yM
This is the only method we have found where nO2 is produced with y greater than 5 and provides an open circuit voltage less than 3.5 when electrochemically combined with lithium.

The mixing is preferably done by dry milling.
) with a maximum particle size of 250 μm.
, preferably a maximum of 50 μm. However, alternatively the mixing can be carried out by wet milling (wet milling) in a suitable liquid.
A slurry of the reagent (sl milling)
The slurry may be dried and heated to obtain a mixture of the reagents.

If desired, the process may be subjected to a suitable pressure, for example 2-10 bar (ie 200-1 bar), prior to heating.
000 kPa) and, if necessary, after drying, the mixture is consolidated by pressing and a step is added to form a green compact which after heating forms a product in the form of a solid unit compact rather than a powder. It's okay.

As mentioned above, the lithium manganese oxide compounds of the present invention can be used as insertion electrodes in both primary and secondary electrochemical cells having lithium as the active material of the electrochemically active anode.
rode).

Thus, yet another aspect of the invention provides an electrochemical cell comprising an anode selected from lithium-containing materials, a cathode, and a suitable electrolyte to which the anode is electrochemically coupled to the cathode. , and the cathode is made of a lithium manganese oxide compound of the formula Li2 O.yMnO2 of the present invention in which the value of y is greater than 5, as described above.

Such a battery is therefore schematically Li(
Anode)/electrolyte/Li2O.yMnO2 (cathode).

[0036] Apart from lithium itself, suitable lithium-containing anodes used include suitable lithium-containing alloys with other metals or non-metallic elements, such as lithium:aluminum and lithium:silicon ratios. These include lithium/aluminum alloys, lithium/silicon alloys, and lithium/carbon anodes in which lithium is inserted into a carbonaceous structure, such as a graphite structure, as used in the art.

The electrolyte is preferably LiClO4 at room temperature.
, LiAsF6, LiBF4 dissolved in an organic solvent such as propylene carbonate, dimethoxyethane, a mixture thereof, etc.

The anode is therefore selected from the group consisting of lithium metal, lithium alloys with other metals, lithium alloys with non-metals, lithium/carbon intercalation compounds and mixtures thereof, and the electrolyte is a room temperature electrolyte, LiClO
4, LiAsF6, LiBF4 and mixtures thereof, dissolved in an organic solvent selected from the group consisting of propylene carbonate, dimethoxyethane and mixtures thereof.

[0039]

[Example] As an example, Li2O・yMnO2 of the present invention
The invention is illustrated by the following examples and figures describing the manufacture and features of the invention.

Details of the various compounds whose X-ray diffraction pattern traces are shown in each figure are given in Table 1 below. In each case, for each figure, whether the compound is a reagent, a reference compound or a lithium manganese oxide compound of the invention, the value of y if the compound has the formula Li2O.yMnO2, the value of y from the reagent according to the method of the invention; If produced, indicate the manganese dioxide reagent when it was produced and the molar ratio of the reagents used. Electrolytically prepared manganese dioxide is abbreviated as EMD, and chemically prepared manganese dioxide is abbreviated as CMD. In the control, Li2 was used as the lithium manganese oxide reagent.
All lithium manganese oxide product compounds of the present invention used Li4 Mn5 O12 as the lithium manganese dioxide reagent.

[0041]

[Table 1]

Table 2 below provides further details for the compounds whose traces are shown in FIGS. 1-9. The control compound and the product compound of the invention were prepared according to the methods described in Examples 1 and 2 to 6 below, respectively. Table 2 shows the reaction temperatures and discharge curves for producing the product compounds of the invention and control compounds of FIGS. 4 and 5 to 9 as cathodes in cells of the type shown in FIGS. 10 to 17. The initial open circuit voltage with the compound in question and the theoretical capacity of the compound as a cathode in such a cell are shown. Table 2 also includes (for comparison purposes)
The values of EMD and CMD reagent compounds (both of which are λ-MnO2) are shown (however, EMD and CMD were heated in advance at 400° C. for 8 hours in air). The reagent compounds of Figure 1 are heated in air at 120°C for 8 hours. The number of tests was repeated and the respective values are shown in Table 2.

[0043]

[Table 2]

Table 2 shows that according to the invention Li2O.
We show that yMnO2 compounds can be prepared with values of y greater than 5, and that the compounds give initial voltages of less than 3.5 V when combined with Li/Li+ in electrochemical cells of the type in question.

Regarding the discharge curves shown in FIGS. 10 to 17, the battery in question was discharged at a discharge current of 500 μA/cm2.
Table 3 below shows the battery capacity until the final discharge voltage of 2V is reached for the batteries whose discharge curves are shown in FIGS. 10 to 17.

[0046]

[Table 3]

Example 1 In this example, Li2 O.yMnO2 reagent compound was mixed with Li2 CO3 and MnCO3 in appropriate proportions to obtain a mixture with an atomic ratio of Li:Mn=1:2. Both particle diameters are 50μ
By grinding to less than m, the formula Li2 Mn4 O
9 (ie, corresponding to y=4 in Li2O.yMnO2) was first produced. The mixture in the air 42
Heating at 0°C for 5 hours produced Li2Mn4O9 with an essentially single-phase spinel structure (see Figure 2).

Separately, a λ-MnO2 reagent was prepared by reacting stoichiometric LiMn2O4 and 1M HCl together for 24 hours at 25°C (see Figure 1).

[0049] Li2 Mn4 O9 and λ-MnO2
were first ground and mixed to a particle size of less than 50 μm and then heated in air at 240° C. for 16 hours. Li2 Mn
The molar ratio of 4O9:λ-MnO2 is selected such that the atomic ratio of Li:Mn is 2:5, and L with y=5.
i2O.yMnO2 was obtained (see Figure 4).

Example 2 The same procedure as in Example 1 was carried out except that the Li2 O.yMnO2 reagent compound initially produced was Li2 O.yMnO2 (ie, Li4 Mn5 O12) with y=2.5. Li4Mn5O12 and λ-MnO2 were heated together at 400°C for 10 hours at a molar ratio of 1:11.5 to obtain a Li2O.yMnO2 product compound in which y was 8.25 (see Figure 5). .

[0051] Li4Mn5O12 was replaced with Li4Mn5O12 in Example 1.
2 Mn4 O9 reagent was prepared in a similar manner, but the starting materials Li2 CO3 and MnCO3 were replaced with Li2 CO3 to obtain an atomic ratio of Li:Mn = 4:5 in the mixture.
CO3: MnCO3 is mixed in an appropriate ratio, 42
Heat at 0°C for 5 hours.

Example 3 The same procedure as in Example 2 was carried out using EMD instead of λ-MnO2. The molar ratio of Li4Mn5O12:EMD was 1:10, and the reaction between Li4Mn5O12 and EMD was carried out at 375°C for 48 hours to form Li with y of 7.5.
A 2 O.yMnO2 product compound was obtained (see Figure 6).

Example 4 The molar ratio of Li4Mn5O12:EMD was 1:12.
5, the reaction between Li4 Mn5 O12 and EMD is 350
℃ for 16 hours to obtain a Li2O.yMnO2 product compound in which y is 8.75 as in Example 3 (Fig. 7
reference).

Example 5 Using CMD instead of EMD, Li4 Mn5 O1
Example 3 was carried out in the same manner as in Example 3, except that the reaction between 2 and CMD was carried out at 400° C. for 24 hours. (See Figure 8).

Example 6 The same procedure as in Example 5 was carried out, except that the molar ratio of Li4Mn5O12:CMD was set to 1:15, and the reaction between Li4Mn5O12 and CMD was carried out at 350°C for 3 days (Fig. 9 reference).

[0056] X-ray diffractogram
tion traces) are used as described above and are illustrated in the drawings referred to in the table above.

FIGS. 1 to 3 show the corresponding λ-Mn
O2 , Li2 Mn4 O9 and Li4 Mn5
It shows the essentially single-phase nature of O12.

FIG. 4 shows that the control Li2O.5MnO2 prepared according to the method of the present invention also has single-phase characteristics, in which only negligible traces of Mn2O3 impurities are observed. It shows.

FIG. 5 shows that the inventive Li2 O.
It shows that traces of -MnO2, β-MnO2 and Mn2O3 are recognized as impurities.

FIG. 6, FIG. 7, FIG. 8 and FIG. 9 show that the product of the present invention, namely Li2O.yMnO2 with y>5,
It is shown to contain a significant component with a spinel-type structure and, in addition, a γ-MnO2 related phase that appears to contain a minor proportion of lithium ions.

The advantage of the present invention is that the Li2O.y of the present invention
The MnO2 product compound is used as a battery electrode in conjunction with a Li/Li+ anode to provide a very high electrode capacity (e
electrode capacities). It is shown in Table 2, especially in Figure 5 (y=
8.25) and Figure 9 (y=10), respectively, with y
= 4, y = 2.5 (Fig. 2, Fig. 3) and the control (y = 5, Fig. 4). However, the relatively low capacity obtained with the λ-MnO2 reagent (see Figures 12 and 13) is attributable to the low surface area of this reagent (10 m2/g
(less than). Higher capacities can be expected when λ-MnO2 reagents with higher specific surfaces are used.

On the other hand, the batteries of the present invention exhibit a particularly high capacity during their initial discharge cycle, and even when these batteries are repeatedly charged and discharged cycled, they exhibit a capacity of 140 mA-h/g.
Achieved a battery capacity exceeding . This is evident from Figure 14, which shows the first six discharge cycles of the cell in question. The initial open circuit voltage of the battery is 3.40V, but as shown in FIG. 14, in the cyclic experiment, the upper and lower voltage limits were set to 3.8V and 2.0V, respectively. This confirms that the product compounds of the present invention have utility in primary and rechargeable (secondary) electrochemical cells.

A further advantageous feature of the battery of the present invention is 3.
If the initial open circuit voltage is less than 5V, the EM
D, CMD or λ-MnO2 (all 3.5
(greater than V, see Table 2). For example, as shown in Table 2, the λ-MnO2 cathode has a 4.
It shows an initial open circuit voltage of 12V, and EMD and CMD show initial open circuit voltages of 3,56V and 3,62V, respectively. However, the above-mentioned Li2O・2.5
Li2O・yMn like MnO2 (y=2.5)
After reaction with O2 reagent, the open circuit voltage will be less than 3.5V. The battery of the invention, in contrast to known batteries, thus does not need to be partially pre-discharged by the manufacturer before being stored, in order to prevent self-discharge, and can be stored for an acceptable period of time. It can be made to promote longevity.

[Brief explanation of the drawing]

FIG. 1: Regarding the λ-MnO2 reagent used in the method of the present invention,

##STR1## Using radiation, the range is 10-
Counts (c
X-ray diffraction pattern trace (pa
ttern trace).

FIG. 2: Li2 Mn4 O9 (Li2 with y=4) used to prepare control compounds in the process of the invention;
A similar diagram is shown for the O.yMnO2) reagent.

FIG. 3 shows a similar diagram for the Li4Mn5O12 (Li2O.yMnO2 with y=2.5) reagent used to prepare the compounds of the invention in the process of the invention.

FIG. 4: y=5 produced according to the method of the invention
A similar diagram is shown for the control Li2O.yMnO2 compound.

FIG. 5 shows a similar diagram for the Li2O.yMnO2 product compound of the present invention and with y of 8.25 prepared according to the method of the present invention.

FIG. 6 shows a similar diagram for the Li2O.yMnO2 product compound of the present invention and with y of 7.5 prepared according to the method of the present invention.

FIG. 7 shows a similar diagram for the Li2O.yMnO2 product compound of the present invention and with y of 8.75 prepared according to the method of the present invention.

FIG. 8 shows a similar diagram for the Li2 O.yMnO2 product compound of the present invention and prepared according to the method of the present invention with y of 7.5.

FIG. 9 shows a similar diagram for the Li2O.yMnO2 product compound of the present invention and with y=10 prepared according to the method of the present invention.

FIG. 10: 1M LiClO4 is dissolved in a solution containing lithium as an anode material, γ-MnO2 as a cathode, and a mixture of propylene carbonate and dimethoxyethane at a volume ratio of 1:1 as an electrolyte. For the control battery, which is a liquid containing
) is the discharge curve (d
ischarge curve).

FIG. 11: A solution containing lithium as an anode material, a λ-MnO2 reagent whose trace is shown in FIG. 1 as a cathode, and a mixture of propylene carbonate and dimethoxyethane in a volume ratio of 1:1 as an electrolyte. The capacity (c) when operated at room temperature (20-25°C) is
The discharge curve is a plot of the voltage versus the apacity.
e) is shown.

FIG. 12 has lithium as the anode material, a control compound Li2O.yMnO2 with y=5 whose trace is shown in FIG. Regarding the control battery, in which 1M LiClO4 was dissolved in a solution mixed at a ratio of
) is a discharge curve (d
ischarge curve).

FIG. 13 shows discharge curves for similar cells of the invention in which the cathodes are each a lithium manganese oxide product compound whose trace is shown in FIG.

FIG. 14 shows discharge curves for similar cells of the invention in which the cathodes are each a lithium manganese oxide product compound whose trace is shown in FIG.

FIG. 15 shows discharge curves for similar cells of the invention in which the cathodes are each a lithium manganese oxide product compound whose trace is shown in FIG.

FIG. 16 shows discharge curves for similar cells of the present invention in which the cathodes are each a lithium manganese oxide product compound whose trace is shown in FIG.

FIG. 17 shows discharge curves for similar cells of the invention in which the cathodes are each a lithium manganese oxide product compound whose trace is shown in FIG.

Claims (15)

[Claims] Claim 1: General formula: Li2O・yMnO2 (where y is a value greater than 5, the Mn cations are substantially all tetravalent, and are combined with lithium by a suitable electrolyte in an electrochemical cell) Then, this compound is 3.
open circuit voltage less than 50V
Lithium manganese oxide compound with oltage). 2. A compound according to claim 1, having as separate phases therein a lithium manganese oxide component and a manganese oxide component with a spinel-type structure. 3. A compound according to claim 2 having an essentially single-phase spinel structure. Claim 4: When combined with lithium in the battery, 3
．． 4. A compound according to any one of claims 1 to 3, characterized in that it supplies an open circuit voltage of less than 40V. 5. A compound according to claim 4, characterized in that the open circuit voltage is less than 3.35V. 6. Compound according to claim 1, characterized in that at most 20% of the manganese cations are replaced by other metal cations. 7. General formula Li2O according to claim 1.
yMnO2, wherein the manganese oxide reagent and the ratio of lithium to manganese ions are ≧1:2.
．． A method consisting of reacting a lithium manganese oxide reagent with a lithium manganese oxide reagent having a particle size of up to 25
Mix thoroughly and uniformly in a 0 μm finely pulverized state, and then heat the mixture at 150-450°C in an oxidizing atmosphere containing oxygen.
The method comprises the step of heating at a temperature in the range of for at least 8 hours. [Claim 8] The reagent has a particle size of at most 50 μm and 20 μm.
It has a specific surface area larger than m2/g and the temperature is 240-
400°C, heating time is 8-18 hours,
8. A method according to claim 7, characterized in that the oxidizing atmosphere is selected from air, oxygen and mixtures thereof. 9. The lithium manganese oxide reagent has a spinel structure and has the formula Li2O.
yMnO2, and the manganese oxide reagent is λ-M
9. The method of claim 7 or 8, wherein the manganese dioxide is selected from the group consisting of nO2, electrolytically prepared manganese dioxide, chemically prepared manganese dioxide and mixtures thereof. 10. The manganese dioxide reagent is λ-M
10. Process according to claim 9, characterized in that the heating is carried out at a temperature of 240-400 DEG C. to obtain a substantially single-phase product. 11. The manganese dioxide reagent is selected from electrolytically prepared manganese dioxide, chemically prepared manganese dioxide and mixtures thereof, heating is carried out at a temperature of 350-400°C, and the spinel 10. Process according to claim 9, characterized in that a product is obtained which consists of components with a manganese dioxide phase in addition to components with a type phase. [Claim 12] y of Li2 O・yMnO2 reagent
Claims 9 to 11 characterized in that the value of is 2.5.
The method described in any of the above. 13. Before heating, 2-10 bar (20
0-1000 kPa) to solidify the mixture by pressing it at a pressure of 0-1000 kPa) to form a green body which after heating forms a product in the form of a solid integrated body. A method according to any one of claims 7 to 12. 14. An electrochemical cell comprising an anode selected from lithium-containing materials, a cathode, and a suitable electrolyte to which the anode is electrochemically coupled, the cathode comprising a lithium manganese oxide compound according to claim 1. A battery consisting of 15. The anode is selected from the group consisting of lithium metal, lithium alloys with other metals, lithium alloys with non-metals, lithium/carbon intercalation compounds and mixtures thereof, and the electrolyte is a room temperature electrolyte, LiClO
15. The organic solvent of claim 14, wherein the organic solvent is selected from the group consisting of 4, LiAsF6, LiBF4, and mixtures thereof, and is dissolved in an organic solvent selected from the group consisting of propylene carbonate, dimethoxyethane, and mixtures thereof. battery.