JPH05201733A - Manganese dioxide material - Google Patents

Abstract

PURPOSE: To prepare the manganese dioxide-based material that is used mainly for electrochemical applications, typically for electrochemical conduction anodes, electrochemical conduction cathodes, and electrodes for electrochemical cells with electrochemical insulating electrolytes to isolate the anode from the cathode.

CONSTITUTION: This manganese dioxide-based material is highly crystalline and chemically prepared. The material has a predominantly ramsdellite structure, and has a powder X-ray diffraction pattern (CuKα radiation) in which the ratio of a [110] peak height to a [201] peak height is at least 0.6:1.0.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a manganese dioxide-based material and an electrochemical cell containing the material.

[0002]

DISCLOSURE OF THE INVENTION In a first aspect of the present invention, a highly crystalline, chemically prepared, preferentially ramsdellite structure and [201] peak height of [110] peak height. A manganese dioxide-based material having a powder X-ray diffraction pattern having a ratio to at least 0.6: 1.0 is provided.

The material is primarily for electrochemical applications, typically an electrochemically conductive anode, an electrochemically conductive cathode,
And as an electrode material in an electrochemical cell having an electrochemically insulating electrolyte that separates the anode from the cathode.

The material can therefore be used as positive electrode or cathode material in batteries with aqueous or non-aqueous electrolytes, for example using zinc or lithium anodes, or negative electrodes, respectively. It is believed that it will find particular, but not necessarily exclusive, application as a positive electrode material in primary or rechargeable lithium batteries.

This material has a small proportion of β-MnO as a gap growth layer in combination with a preferential Ramsdellite structure.
₂ , MnO _{2 including a} rutile structure may be included.

The material can further include a minority proportion of lithium or hydrogen to stabilize the ramsdellite structure. In this regard, Ramsdellite-MnO ₂
Does not necessarily have to be a stoichiometric compound having a Mn: O ratio of 1: 2 and a manganese ion oxidation state of 4.0, and a manganese ion oxidation state of 4.0 or less and 3.5 or more. , Preferably Mn: O such that it is 3.8 or more.
It may be a compound in which the ratio deviates slightly from 1: 2.

In the powder X-ray diffraction pattern, the ratio of the [110] peak height to the [201] peak height is at least 0.8: 1.0, typically about 1.0: 1.0, It shows a high degree of crystallinity and monophasicity of the ramsdellite manganese dioxide structure. The [110] peak appears at about 22 ° 2θ, and the [201] peak appears at about 37 ° 2.
Appears in θ. In the powder X-ray diffraction image, the ratio of the [110] peak height to the [221] peak height was about 56.
At least 1.2: 1.0 appears in ° 2θ,
This again shows the high degree of crystallinity of ramsdellite manganese dioxide. The ratio of [110] peak height to [221] peak height may be about 1.4: 1.0.
The [110] peak has a peak width of less than 2 ° 2θ at half maximum of the peak height, that is, a peak width of about 1.5 ° 2θ, which also indicates the high degree of crystallinity of ramsdellite manganese dioxide.

The material is prepared by reacting a lithium-manganese dioxide compound with concentrated acid. The acid is sulfuric acid and its concentration is at least 2M. When concentrated acid is used to dissolve the lithium-manganese dioxide compound, the synthesized ramsdellite-MnO ₂ structure becomes highly crystalline. The advantage of the high crystallinity of the ramsdellite structure or phase is that ramsdellite-MnO _{2 with} cycling in rechargeable Li / ramsdellite-MnO ₂ electrochemical cells.
₂ Structural completeness of electrochemically prepared MnO ₂
It is believed to be superior to those obtained from known γ-MnO ₂ electrodes such as ('EMD'). Another advantage of the Ramsdellite MnO ₂ structure is the known chemically prepared MnO ₂ ('CMD') material and EMD.
It is to provide a higher initial discharge capacity for primary battery applications compared to products.

The lithium-manganese-oxide precursor compound may be a stoichiometric spinel compound such as LiMn ₂ O ₄ , or Li ₂ O. It is selected from defect spinel compounds such as those found in the yMnO ₂ system, for example Li ₂ Mn ₄ O ₉ (y = 4) or Li ₂ Mn ₃ O ₇ (y = 3).

These precursor compounds can typically be synthesized, for example, by reacting manganese carbonate (MnCO ₃ ) and lithium carbonate (Li ₂ CO ₃ ) at a required ratio at a predetermined temperature.

[0011]

[Chemical 1]

[0012]

[Chemical 2]

[0013]

[Chemical 3]

The lithium-manganese-oxide spinel precursor compound dissolves in concentrated sulfuric acid, such as 2.6 MH ₂ SO ₄ , at high temperature, such as 95 ° C., for a few hours to efficiently dissolve all lithium and give it a highly crystalline structure. Rams Delight-
This produces a MnO ₂ phase. For example, when complete, the ideal reaction is:

[0015]

Embedded image 2LiMn ₂ O ₄ → 3MnO ₂ + MnO + Li ₂ O Li ₂ Mn ₄ O ₉ → 4MnO ₂ + Li ₂ O Li ₂ Mn ₃ O ₇ → 3MnO ₂ + Li ₂ O

However, it should be noted that in practice the final ramsdellite phase contains a small amount of lithium or hydrogen which is believed to have a role in stabilizing its structure.

The present invention when produced by the process according ramsdellite -MnO ₂ phase usually contains a small amount of water associated with the surface or grain boundaries of the MnO ₂ particles. Rams Delight-M
The water content is important when nO ₂ is used as an electrode in aqueous batteries, for example using a zinc anode. However, when it is used in lithium batteries, the Ramsdellite-MnO ₂ phase must be heated to 100 ° C. or higher to remove water. In this regard, the Ramsdellite-MnO ₂ phase of the present invention is 250-30
It has been found to be extremely stable up to 0 ° C, but it dislocations to a β-MnO ₂ (rutile type) structure by heat treatment at 300 ° C or higher.

On the other hand, the ramsdellite-MnO ₂ phase is Li
In the presence of a lithium salt such as OH, LiNO ₃ or Li ₂ CO ₃ , optionally in the presence of another lithium manganese oxide phase such as a spinel phase which is formed as a by-product of the reaction, at elevated temperature, ie 200-400 ° C., preferably Is 300-3
Dehydrate at 70 ° C. to produce a lithium stabilized ramsdellite phase. The exact composition range of these phases is not clear, but the overall composition is Li _2x MnO _{2 + x}

[Equation 3] It is believed to be revealed in. The MnO ₂ component in the Li _2x MnO _{2 + x} Ramsdellite related phase does not have to be stoichiometric, but the oxidation state of the manganese cation may be slightly oxygen deficient, such as slightly less than 4.0. It is also necessary to consider that.

While the material is described as suitable for use as an electrode material, it is believed that it can also be used in catalytic applications.

The second aspect of the invention is highly crystalline, preferentially has a ramsdellite structure and a ratio of [110] peak height to [201] peak height of at least 0.6: 1.0. Powder X-ray diffraction image (CuKα line), and the [110] peak is 2 ° 2θ at half peak height.
A manganese dioxide-based material having the following peak width is provided.

The material according to the second aspect of the invention is also chemically prepared as described above and has the relative peak height and peak width as described above.

In a third aspect of the present invention, an electron-conducting anode; a highly crystalline, chemically prepared, preferentially ramsdellite structure, [110] peak height and [20]
1] an electronically conductive cathode made of manganese dioxide having a powder X-ray diffraction pattern (CuKα ray) having a ratio with a peak height of at least 0.6: 1.0; and an electronically insulating electrolyte for separating the anode from the cathode An electrochemical cell including is provided.

The battery is a primary or secondary, ie rechargeable battery, the electrolyte being aqueous or non-aqueous, for example zinc or hydrogen for aqueous electrolytes and lithium for non-aqueous electrolytes.

In a fourth aspect of the present invention, an electron conducting anode; preferentially a ramsdellite structure and a ratio of [110] peak height to [201] peak height of at least 0.
The powder X-ray diffraction pattern (C) is 6: 1.0, and the [110] peak has a half value of the peak height and a peak width of 2 ° 2θ or less.
An electrochemical cell comprising an electron-conducting cathode consisting of highly crystalline manganese dioxide with uKα radiation); and an electron-insulating electrolyte separating the anode from the cathode.

The manganese dioxide is as described above, and particularly has the powder X-ray diffraction pattern as described above.

[0026]

EXAMPLE An electrode material according to the present invention and the following specific examples of batteries, and an outline drawing of the battery according to the present invention (FIG. 1)
The present invention will be described with reference to FIG.

In the figure, 1 mol LiClO ₄ / ramsdellite-MnO ₂ in Li (anode) / propylene carbonate (electrolyte), Teflon, acetylene black (cathode)
Type of battery is shown. The cell is designated 10 and the anode, electrolyte and cathode are designated 12, 14 and 16, respectively. The anode, electrolyte and cathode are housed in an insulating housing 18 with the anode separated from the cathode by an electrolyte and suitable terminals (not shown) are in electronic contact with the anode and cathode, respectively.

In the cathode, Teflon is the binder and acetylene black is the current collector. Powdered ramsdellite -MnO ₂ volume ratio 70 of MnO ₂
-80% is mixed with 30-20% Teflon and acetylene black, but the volume ratio of Teflon and acetylene black is 1: 2 and compressed at 5-10 MPa.

Ramsdellite-MnO ₂ suitable for use in the cathode 16 of cell 10 was prepared according to the following examples.

Example 1 Li ₂ C in a molar ratio of 1: 4 at 800 ° C. for 24 hours in air
A stoichiometric spinel LiMn ₂ O ₄ was prepared by reacting an intimate mixture of O ₃ and MnCO ₃ . Then, the LiMn ₂ O ₄ precursor product was treated with 2.6 MH ₂ SO ₂ at 95 ° C. for 2 days.
Reflux in ₄ and heat. Ramsdellite-M obtained
The powder X-ray diffraction pattern (CuKα ray) of the nO ₂ product is shown in FIG. After drying the product at 100 ° C. overnight, the [H ⁺ ] concentration is 0.16% by weight, indicating that there is some residual water on the surface and occluded water in the structure. After heating the ramsdellite product to 250 ° C., there was no change in the powder X-ray diffraction pattern (FIG. 3), indicating the structural integrity of the ramsdellite phase at this temperature. The hydrogen content [H ⁺ ] of the ramsdellite product heated at 250 ° C was 0.08% by weight.

Ramsdellite-MnO ₂ of the compound of the present invention
The high degree of crystallinity of the phases leads to relatively sharp peaks, especially about 3
22 ° 2θ having a relative peak height of about 1.0: 1.0 for the [201] peak of 7 ° 2θ and about 1.4: 1.0 for the [221] peak of about 56 ° 2θ Is reflected in the sharp and strong [110] peak of. Therefore [110]:
The ratio of [201] and [110]: [221] peak heights indicates that the highly crystalline Ramsdellite-M of the present invention.
For nO ₂ , respectively,> 0.6: 1.0 and> 1.2: 1.0, respectively, as described above. In addition, the [110] peak has a peak width of 2 ° 2θ or less at half peak height, which further indicates the high degree of crystallinity of the Ramsdellite MnO ₂ phase of the compound of the present invention. The structure of the ramsdellite MnO ₂ phase obtained from the profile analysis of this X-ray image is shown in FIG. The result of the analysis is
About 10% of manganese ions represented by ○ in Fig. 4 are (2x
1) It shows that it is located in the channel. This behavior is also believed to be due to the small amount of interstitial growth β-MnO ₂ in the structure.

Insertion of lithium into the ramsdellite phase was shown by reacting 1 molar equivalent of n-butyllithium in hexane with ramsdellite-MnO ₂ at 45 ° C. for 4 days. The powder X-ray diffraction pattern of the lithiated product of composition Li _0.5 MnO ₂ is shown in FIG. Appearance of several new peaks and movement of one peak, eg about 22 °
The shift of the [110] peak of 2 [Theta] to about 19.5 [deg.] 2 [Theta] indicates a modified ramsdellite structure and expanded unit cell. Sharp and well separated peaks, eg [1
The retention of the [10] and [201] peaks indicates that the lithiated phase retains a high degree of crystallinity even after reacting with a strong reducing agent such as n-butyllithium. The modified ramsdellite structure determined by profile analysis of X-ray diffraction images is shown in FIG. It shows that the insertion of lithium is accompanied by distortion of the oxygen planes and the transformation of these planes from hexagonal packing to cubic packing structure.

Crystallographic analysis of the product of FIG. 2 by profile analysis of the X-ray diffraction image shows that the product has a lattice constant a = 9.3.
It was shown to be an almost pure ramsdellite phase with orthorhombic unit cells of 76Å, b = 4.471Å and c = 2.855Å. The partially lithiated phase Li _0.5 MnO ₂ whose X-ray image is shown in FIG. 5 has a lattice constant a = 9.
It was found to have 527Å, b = 5.059Å and c = 2.848Å.

Example 2 A defect spinel Li ₂ Mn ₄ O ₉ (Li ₂ O.4MnO ₂ ) was prepared by reacting an intimate mixture of Li ₂ CO ₃ and MnCO ₃ powder in a molar ratio of 1: 4 at 400 ° C. for 20 hours. Was prepared. Then, the Li ₂ Mn ₄ O ₉ precursor was added to 2.6 MH ₂
Heated at 95 ° C. for 2 days under SO ₄ reflux. The powder X-ray diffraction pattern of the obtained product is shown in FIG. It is very similar to the product of Example 1 (Figure 2).

Example 3 Ramsdellite-MnO ₂ was added to LiNO ₃ and 28 in air.
The reaction was carried out at 0 ° C. for 30 hours and then at 300 ° C. for 20 hours. The Li: Mn ratio of the starting mixture was 3: 7. The powder X-ray diffraction pattern of the product is shown in FIG. The main peaks of the X-ray diffraction image are a = 9.268Å, b = 4.971Å and c =
Li _2x MnO with an orthorhombic unit cell of 2.864Å
Can be assigned to _{2 + x} products.

Example 4 Example 1 heated at 100 ° C. overnight to remove water from the sample
Was evaluated as a cathode material of a lithium battery similar to the battery 10 of FIG. The battery comprises a metallic lithium anode 12 compressed on a stainless steel current collector, an electrolyte 14 containing 1M LiClO ₄ dissolved in a 1: 1 volume ratio of propylene carbonate and dimethoxyethane, and Teflon as a binder and acetylene black. It consisted of a cathode 16 containing about 40 mg of MnO ₂ mixed with about 10 mg of Teflon binder / acetylene black mixtures (Teflon: acetylene black ratio in these mixtures was 1: 1), which acted as a current collector.

The initial discharge curves of three independent lithium batteries according to the present invention are shown in FIG. 9, where the Ramsdellite phase averages about 225 mAh for initial discharge for a cutoff voltage of 2V.
It is shown to act as an efficient cathode material, producing a / g capacity. The open circuit voltage vs. composition x in Li _x MnO ₂ is: Ramsdellite-Mn as shown in FIG.
It shows that O ₂ can receive one Li ⁺ for a cutoff voltage of 2.8V.

Scanning speed 1 mV / sec, voltage range 1.1
Ramsdellite-Mn swept from V to 4.6V
The cyclic voltammogram of O ₂ (FIG. 11) shows that the electrochemical reaction is reversible after the initial discharge cycle.

Rechargeable Li / ramsdellite-Mn
The electrochemical discharge curves for the first 8 cycles of the O ₂ cell are shown in FIG. 12, which shows the cyclic voltometry data and the cells after the first discharge were 100 and 150 mAh / h.
It is intended to produce a rechargeable capacity of between g.

Example 5 The Ramsdellite-MnO ₂ phase prepared by the method of Example 1 but without heat treatment was treated with an alkaline half-cell using a nickel gauze counter electrode (anode), 9M KOH electrolyte, and a Hg / HgO reference electrode. Evaluated in. The cathode is 100
It was composed of 500 mg of Ramsdellite-MnO ₂ mixed with mg of graphite. Half battery with current speed of about 10
It was discharged at mA (Fig. 13). The voltage obtained from this electrode was sufficient, but corresponding to MnOOH-1 V vs. Hg
/ HgO discharge theoretical discharge capacity (308mAh / g)
was gotten.

A particular advantage of the present invention is that it provides a lithium battery potentially suitable for primary or rechargeable use, simple in design, low cost and long shelf life.

Manganese dioxide is known as a cathode material for electrochemical cells using either zinc or lithium anodes with an electronically insulating electrolyte that separates the anode from the cathode. The most common form of manganese dioxide used in this way is the chemically or electrolytically prepared γ-
MnO ₂ , chemical manganese dioxide ('CM
D '), or electrolytic manganese dioxide (' EMD '). γ-MnO ₂ (FIG. 14) is a rutile type MnO ₂ structure (β-MnO ₂ ) (FIG. 15) and ramsdellite type MnO.
₂ (Fig. 16). C
Both MD and EMD contain surface and occluded water and assist the electrochemical discharge reaction when used as a cathode in an aqueous zinc battery system. However, when used in lithium batteries, lithium reacts violently with water, so this surface and stored water, which is believed to be predominantly localized at grain boundaries, must be removed from the manganese dioxide electrode material.
Removes about 80% of water but not all water, 35
The heat treatment of γ-MnO ₂ from 0 to 450 ° C. also leads to the rearrangement of the structure into the so-called γ / β-MnO ₂ phase, ie the phase with increasing rutile (or β-MnO ₂ ) content in the structure.

Rutile-MnO ₂ contains a one-dimensional channel with a cross-sectional area determined by the size of one MnO ₆ octahedron, which channel can therefore be defined as a (1 × 1) channel. The channels in ramsdellite are also one-dimensional, but the cross-sectional area of each channel is two MnO _{6 in} one direction.
Determined by a single MnO ₆ octahedron perpendicular to the octahedron,
Therefore, the channel is defined as a (2x1) channel.

The electrochemical reactions of lithium batteries using transition metal oxide or chalcogenide cathodes often occur in intercalation or phase chemistry, whereby the lithium is transformed into the host transition metal oxide with co-reduction of the host transition metal. / Inserted in chalcogenide structure.

Therefore, β-M having a narrow one-dimensional channel
nO ₂ is not as electrochemically active as γ-MnO ₂ which contains both β-MnO ₂ type (1 × 1) channels and larger ramsdellite type (2 × 1) channels. Crystalline β
Whereas the --MnO ₂ product incorporates only 0.2 Li ⁺ per MnO ₂ unit, the heat treated γ / β-MnO ₂ with both Ramsdellite and rutile channels yields substantially more Li ⁺ ions per chemical unit. take in. Especially, the heat treatment γ / β-MnO ₂ is one L per MnO ₂ unit.
It has been found to react with i ⁺ , but this is not completely reversible, which limits its application to rechargeable lithium batteries.

That is, the larger the proportion of ramsdellite in γ-MnO ₂ is, the larger the lithium uptake capacity into the electrode material becomes, and the larger the recharge capacity of the electrode material becomes. Since the electrode material of the present invention can be synthesized in a totally anhydrous form, the relatively high temperatures required for moisture removal and converting part of the structure into the undesired β-MnO ₂ phase as described above are not required. Furthermore, the desired stability of the ramsdellite structure is found in low concentrations of lithium salt and ramsdellite-
It is induced as described above by the reaction with MnO ₂ .

A simulated powder X-ray diffraction pattern of the ideal MnO ₂ structure is shown in FIG.

Ramsdellite-MnO ₂ has a modified hexagonal packed ('hcp') oxygen anion arrangement. In such an arrangement, the octahedra defined by the oxygen lattice share corners with each other, while others share faces. Rams Delight-Mn
With O ₂ , therefore, it is unlikely that all of the interstitial octahedral sites of the structure will be filled by the simultaneously inserted lithium ions, due to electrostatic interactions of the cations in the face-shared octahedra. Therefore, Ramsdellite-Mn
In O ₂ , only a very small part of the interstitial sites are filled with lithium ions before the oxygen ion arrangement is rearranged to cubic packing and becomes a distorted structure that is essentially more stable than the original deformed hexagonal packed parent structure. It is believed that it will be

After the first discharge, not all lithium ions were easily removed from the structure by charging the cell, and a low concentration of Li ⁺ ions remained in the channels of the modified Ramsdellite phase to stabilize the structure. Has been done.

[Brief description of drawings]

FIG. 1 is a schematic view of a battery according to the present invention.

FIG. 2 is a trace diagram of a powder X-ray diffraction image of a product according to an example of the present invention.

FIG. 3 is a trace diagram of a powder X-ray diffraction image after heating the product.

FIG. 4 is a structural diagram showing a ramsdellite MnO ₂ structure obtained by profile analysis of an X-ray image.

FIG. 5 is a trace diagram of a powder X-ray diffraction image of a lithiated product.

FIG. 6 is a structural diagram showing a modified ramsdellite structure obtained from profile analysis of an X-ray image.

FIG. 7 is a trace diagram of a powder X-ray diffraction pattern of a product according to another example of the present invention.

FIG. 8 is a trace diagram of a powder X-ray diffraction pattern of a product according to another example of the present invention.

FIG. 9 is a relationship diagram showing an initial discharge curve of an independent lithium battery according to the present invention.

FIG. 10 is a relationship diagram between composition x and open circuit voltage in Li _x MnO ₂ .

FIG. 11 is a cyclic voltammogram diagram of a battery according to the present invention.

FIG. 12 is a relational diagram showing the discharge curves of the first 8 cycles of the battery according to the present invention.

FIG. 13 is a relational diagram showing a discharge curve of a half-cell according to the present invention.

FIG. 14 is a structural diagram showing a γ-MnO ₂ structure.

FIG. 15 is a structural diagram showing a β-MnO ₂ structure.

FIG. 16 is a structural diagram showing a Ramsdellite type MnO ₂ structure.

FIG. 17 is a trace diagram of a simulated powder X-ray diffraction image of an ideal MnO ₂ structure.

[Explanation of symbols]

 10 Battery 12 Anode 14 Electrolyte 16 Cathode 18 Insulation Housing

 ─────────────────────────────────────────────────── ─── of the front page continued (72) inventor Michael Makepeace Sakkarei Republic of South Africa, Transvaal Provincetown, Pretoria, Lynnwood Lippo di, Karibaea Street 153 (72) inventor Margarita Hendorina Rosou Republic of South Africa, Transvaal Provincetown, Pretoria , Lietofontin, Twentyforce Avenue 822

Claims (22)

[Claims] 1. A highly crystalline, chemically prepared, preferentially ramsdellite structure and having a ratio of [110] peak height to [201] peak height of at least 0.6: 1.0. A manganese dioxide-based material having a powder X-ray diffraction image (CuKα ray) which is 2. A manganese dioxide-based material according to claim 1, which comprises a minority proportion of β-MnO ₂ as interstitial growth in combination with a preferential ramsdellite structure. 3. A small proportion of lithium or hydrogen for stabilizing the ramsdellite structure is included, and the Mn: O ratio of ramsdellite MnO ₂ is 3.5 even though the oxidation state of manganese ion is 4.0 or less. The manganese dioxide-based material according to claim 1 or 2, which is slightly deviated from 1: 2 as described above. 4. The powder X-ray diffraction image, wherein the ratio of the [110] peak height to the [201] peak height is at least 0.8: 1.0. The described manganese dioxide-based material. 5. The ratio of the [110] peak height to the [201] peak height in the powder X-ray diffraction image is about 1.
The manganese dioxide-based material according to claim 4, which is 0: 1.0. 6. The powder X-ray diffraction pattern has a ratio of [110] peak height to [221] peak height of at least 1.2: 1.0, which indicates a high degree of crystallinity of the ramsdellite manganese dioxide structure. The manganese dioxide-based material according to any one of claims 1 to 5, comprising: 7. The ratio of the [110] peak height to the [221] peak height in the powder X-ray diffraction image is about 1.
The manganese dioxide-based material according to claim 6, which is 4: 1.0. 8. The powder [110] peak in a powder X-ray diffraction pattern has a peak width of 2 [deg.] 2 [theta] or less, which further indicates a high degree of crystallinity of the ramsdellite manganese dioxide structure at half peak height. The manganese dioxide material according to any one of 1 to 7. 9. The manganese dioxide-based material according to claim 8, wherein the [110] peak in the powder X-ray diffraction image has a peak width of about 1.5 ° 2θ at half maximum of the peak height. 10. When reacted with a lithium salt, 10. The manganese dioxide-based material according to any one of claims 1 to 9, which results in a lithium-stabilized phase represented generically by Li _2x MnO _{2 + x} . 11. A highly crystalline and preferentially ramsdellite structure, wherein the ratio of [110] peak height to [201] peak height is at least 0.6: 1.0, and the [110] peak is Is a manganese dioxide-based material having a powder X-ray diffraction image (CuKα ray) having a peak width of 2 ° 2θ or less at half peak height. 12. An electron-conducting anode; preferentially having a ramsdellite structure and having a [110] peak height of [201]
An electronically conductive cathode comprising highly crystalline and chemically prepared manganese dioxide having a powder X-ray diffraction pattern (CuKα line) having a ratio to peak height of at least 0.6: 1.0; and An electrochemical cell including an electronically insulating electrolyte that separates an anode from a cathode. 13. The cathode also has a minority proportion of β-M as interstitial growth combined with a preferential ramsdellite structure.
The electrochemical cell according to claim 12, comprising nO ₂ . 14. The cathode also contains a minority ratio of lithium or hydrogen to stabilize the ramsdellite structure, and the Mn: O ratio of ramsdellite MnO ₂ is such that the oxidation state of manganese ions is 4.0 or less. 14. The electrochemical cell according to claim 12 or claim 13, wherein S is slightly off from 1: 2 such that it is 3.5 or more. 15. The ratio of the [110] peak height to the [201] peak height in the powder X-ray diffraction pattern of manganese dioxide is at least 0.8: 1.0.
The electrochemical cell according to any one of claims 1 to 14. 16. The electrochemical cell according to claim 15, wherein the ratio of the [110] peak height to the [201] peak height in the powder X-ray diffraction pattern of manganese dioxide is about 1.1: 1.0. 17. In the powder X-ray diffraction pattern of manganese dioxide, the ratio of the [110] peak height to the [221] peak height is at least 1.2: 1.0, and the ratio of the ramsdellite manganese dioxide structure is high. The electrochemical cell according to any one of claims 12 to 16, which also exhibits crystallinity. 18. The electrochemical cell according to claim 17, wherein the ratio of the [110] peak height to the [221] peak height in the powder X-ray diffraction pattern of manganese dioxide is about 1.4: 1.0. 19. In the X-ray diffraction pattern of manganese dioxide powder, the [110] peak has a peak width of 2 ° 2θ or less at half peak height, which further indicates a high degree of crystallinity of the ramsdellite manganese dioxide structure. Claims 12-18
The electrochemical cell according to any one of claims 1. 20. In the X-ray diffraction pattern of manganese dioxide powder, the [110] peak has a half value of the peak height of about 1.5 °.
20. The electrochemical cell according to claim 19, having a peak width of 2 [Theta]. 21. When reacted with a lithium salt, manganese dioxide has the formula: Li _2x electrochemical cell according to any one of at MnO 2 + _x including the claims 12-20 to produce a lithium-stabilized phases generically revealed it. 22. An electron-conducting anode; preferentially having a ramsdellite structure and having a [110] peak height of [201]
The ratio to the peak height is at least 0.6: 1.0 and the [110] peak height is 2 ° 2 at half the peak height.
Powder X-ray diffraction image (CuKα line) with a peak width of θ or less
An electrochemical cell comprising a highly crystalline manganese dioxide containing electron-conducting cathode having; and an electron-insulating electrolyte separating the anode from the cathode.