MXPA96006092A - Composite of lithium-manganese oxide and method for preparing - Google Patents

Abstract

A method for the preparation of Li2MbMn2-bO4 comprising the steps of providing LiMbMn2-bO4, providing a lithium source, dissolving lithium from the lithium source in a liquid medium wherein the lithium generates solvated electrons or the reduced form of a catalyst of electron transfer, and contacting the LiMbMn2-bO4 with the liquid medium containing the dissolved lithium and the solvated electrons or the reduced form of the electron transfer catalyst, wherein M is selected from the group consisting of Al, Ti, V, Cr, Fe, Co, Ni and

Description

COMPOUND OF LITHIUM-MANGANESE OXIDE AND METHOD FOR YOUR PREPARATION FIELD OF THE INVENTION The present invention relates to lithiated manganese-multicomponent oxide compounds (Li2MbMn2_b04) and their production by contacting LiMbMn2.b04 with lithium dissolved in a solvent, where lithium generates solvated electrons or where it is present a catalyst that is capable of accepting a lithium electron and supplying it to LiMbMn2.b04. BACKGROUND OF THE INVENTION The present invention relates to lithiated manganese-multicomponent oxides, with methods for the preparation of such materials and with the use of the latter in the manufacture of cathodes for batteries and electrodes for other purposes such as in electrochemical cells. More particularly, the invention relates to a process for the preparation of Li2MbMn2.b04 and to the use of Li2MbMn2.b04 in electric accumulators. Even more particularly, the invention relates to a process for the preparation of Li2MbMn2.b04 by the reaction of LiMbMn2.b04 with lithium and the use of Li2MbMn2.b04 in the manufacture of the cathode component of rechargeable lithium-ion electric accumulators. . Traditionally used non-aqueous electrolyte batteries are primary batteries that can only be used once. With the recent increasing use of video cameras and small audio instruments, there is also an increasing need for secondary batteries that can be used conveniently and economically during many charge-discharge cycles. Lithium batteries useful as electric accumulators incorporate a metallic lithium anode and a cathode that includes an active material that can absorb lithium ions. An electrolyte incorporating lithium ions is disposed in contact with the anode and the cathode. During the discharge of the batteries, the lithium ions leave the anode, enter the electrolyte and are absorbed in the active material of the cathode, translating this into the release of electrical energy. As long as the reaction between the lithium ions and the cathodic active material is reversible, the process can be reversed by applying electrical energy to the battery. If said reversible active cathode material is provided in a stack having the appropriate physical configuration and a suitable electrolyte, the stack can be recharged and reused. Rechargeable batteries are commonly known in the industry of electric accumulators as secondary batteries. It has been known for some time that useful batteries can be prepared with a metallic lithium anode and a cathode material consisting of a sulfide or oxide of a transition metal, that is, a metal capable of assuming various and different valence states. Dampier, "The Cathodic Behavior of CuS, Mo03 and Mn02 in Lithium Cells ", J.

Electrochem. Soc., Vol. 121, No. 5, pp. 656-660 (1974) discloses that a battery incorporating a lithium anode and an active cathodic manganese dioxide material can be used as a source of electrical energy. The same reference further describes that a lithium and manganese dioxide battery can serve as a secondary battery. In the field of electric accumulators considerable effort has been devoted to the development of cathode materials based on lithium-manganese oxide. Both lithium and manganese dioxide are relatively inexpensive, easily obtainable materials, which offer the possibility of obtaining a powerful and useful accumulator at a low price. Primary non-aqueous electrolyte batteries that use lithium as the negative electrode active material and a non-aqueous solvent, such as an organic solvent as an electrolyte medium, have advantages since self-discharge is low, nominal power is high and storage capacity is excellent. Typical examples of such nonaqueous electrolyte cells include primary lithium-manganese dioxide cells which are widely used as current sources for watches and memory storage of electronic instruments as a consequence of their long-term reliability. Secondary lithium batteries that use an intercalation compound such as cathode and free lithium metal as anode, have been studied intensively due to their potential technological importance. Unfortunately, these studies have revealed that the inherent dangers associated with the use of free lithium discourage the use of such batteries in general consumption applications. After repeated siclation, lithium dendritic growth occurs at the lithium electrode. The growth of lithium dendrites can eventually lead to an internal short circuit in the cell with the consequent dangerous uncontrolled release of the energy stored in the cell. One approach to improving the reversibility of lithium-based anodes involves the use of lithium intercalation compounds. The intercalation compound serves as the host structure for the lithium ions which are stored or released depending on the polarity of an externally applied potential. During unloading, the electromotive force inverts the forced intercalation, thereby producing current. Batteries using this solution, where an intercalation compound such as the anode is used instead of free lithium metal, are known in the art as "lithium ion" or "rocking" batteries. The use of Li2Mn204 in secondary lithium ion batteries is described in detail in a recent journal entitled "The Li1 + aMn204 / C Rocking-chair System", J.M. Tarascon and D. Guyomard, Electrochimica Acta, Vol. 38, No. 9, pp. 1221-1231 (1993). According to this approach, a non-aqueous secondary cell is provided with (a) a negative electrode consisting essentially of a carbonaceous material as support for a negative electrode active material, said support being capable of being doped and undoped with lithium, and (b) a positive electrode comprising lithium-manganese complex oxide as an essential positive electrode active material. This stack has a high application capacity expected because the precipitation of lithium dendrites does not occur on the surface of the negative electrode, the lithium spray is inhibited, the discharge characteristics are good and the energy density is high. The output voltage of this lithium ion battery is defined by the chemical potential difference of the two insertion compounds. Therefore, the cathode and the anode must comprise intercalation compounds that can intercalate lithium at high and low voltages, respectively. The viability of this concept has been demonstrated and the future commercialization of these batteries in D, AA or coin type cumulators has been demonstrated. These batteries include a cathode of LiMn204, LiCo02 or LiNi02, an electrolyte and a carbon anode. It is believed that these lithium ion batteries are superior to nickel-cadmium batteries and that they do not require a controlled environment for their manufacture because the lithium-based cathode is stable in an ambient atmosphere, and the anode does not consist of metal free lithium, but in an intercalation compound used in its discharged state (without intercalated lithium) which is also stable in an ambient atmosphere. However, a secondary battery of nonaqueous electrolyte, such as that described above, has drawbacks since part of the capacity of the cell is lost as a consequence of part of the doped lithium in the carbonaceous material used as active material of negative electrode does not It can be undocked after the download. In practice, both carbon and graphite irreversibly consume a portion of the lithium during the first charge-discharge cycle. As a result, the capacity of the electrochemical cell decreases in proportion to the lithium that is irreversibly intercalated into the carbon during the first charge. This drawback can be eliminated by using Li2Mn204 as the whole or as part of the cathode. After the first charge of the battery thus manufactured, the Li2Mn204 is converted to? -MN204. When the battery operates in the proper range of electric potential, will subsequent battery discharge cycles convert? -Mn204 to LiMn204, and the charge cycles convert LiMn204 to? -Mn204. Because an excess of lithium is available to satisfy the irreversible consumption by carbon or graphite, the batteries manufactured using Li2Mn204 have a higher electrical capacity. The capacity of a lithium ion battery is also limited by the amount of lithium that can be removed (ie, cyclized) reversibly from the cathode. In cathodic materials of the prior art, only about one mole of lithium can be reversibly separated by transition metal. In this way, said materials have a limited specific capacity, generally not exceeding approximately 140 mAh / g. In principle, one mole of lithium per mole of manganese can be reversibly separated from Li2Mn204. However, in practice, batteries cycling between Li2Mn204 and LiMn204 experience a faster loss of electrical capacity than batteries cycling between LiMn204 and? -Mn204. In addition, batteries that cycle between LiMn204 and? -Mn204 supply most of their electric power between 4 volts and approximately 3 volts, while batteries that cycle between Li2Mn204 and LiMn204 supply most of their electric power between 3 volts and 2 volts approximately. Therefore, a combination of factors provides a lithium ion battery that cyclizes lithium between a carbon or graphite matrix as an anode and LiMn204 as a fully discharged cathode, offering many particularly attractive features. Said piles can be conveniently assembled in an over-discharged state using carbon or graphite for the anode and Li2Mn204 for the cathode. Because the second lithium ion can not be used in an efficient manner for repeated cyclization, its consumption to satisfy the irreversible lithium intercalation of the carbonaceous anodic material does not entail any additional loss of electrical capacity. The LiMn204 and Li2Mn204 compounds which are useful in this invention are known in the art. Depending on the preparation methods, their stoichiometries may differ slightly from the ideal. However, they are precisely identified by their X-ray powder diffraction patterns. The materials referred to herein as LiMn204 and Li2Mn204 have the diffraction spectra offered on cards 35-781 and 38-299, respectively. of the Powder Diffraction File published by the International Center for Diffraction Data, Newtown Square Corporate Campus, 12 Campus Boulevard, Downtown Square, Pennsylvania, 19073-3273, USA. Materials designated as LiMbMn2.b04 and Li2MbMn2.b04 where M represents a metal other than manganese, which are the subject of this invention, are essentially insoestructurales with LiMn204 and Li2Mn204, respectively, and have powder diffraction spectra that differ from those of LiMn204 and Li2Mn204 only in small displacements of the corresponding diffraction peaks and in small differences in their relative intensities. The LiMn204 can be prepared from a wide range of lithium sources and a wide range of manganese sources, under a wide range of conditions. US 5,135,732 describes a method for the preparation at low temperature of LiMn204. The LiMbMn2.b04 materials can be prepared under a wide range of conditions by substituting an amount of the manganese source corresponding to ab moles of manganese per mole of lithium by an amount of an alternative metal source, M, corresponding ab moles of alternative metal by lithium mol, Y. Bito, et al. r Proc. Electrochem. Soc. (1993), 93-23, 461-472; Y. Toyoguchi, US 5,084,366, January 28, 1992. The range of conditions in which LiMbMn2.b04 can be synthesized varies with metal M and with b, the proportion of M in the compound. In general, the synthesis is easier as the value of b is smaller. The compound LiMbMn2.b04 is a starting material for the present invention. On the contrary, Li2Mn204 is more difficult to prepare and, in fact, the known methods for the preparation of Li2Mn204 are excessively expensive. The preparation of the substituted compounds Li2MbMn2.b04 and their use in rechargeable batteries constitute the objects of this invention. In the manufacture of cathodes for rechargeable lithium ion batteries, this material has the advantages that are attributed to the use of Li2Mn204 as described above. In addition, the Li2MbMn2.b04 materials produce cathodes having either a higher electrical storage capacity or a higher cyclization capacity, or both, compared to cathodes similarly prepared on the basis of Li2Mn204. SUMMARY OF THE INVENTIONAn object of the present invention is to provide a secondary non-aqueous electrolyte cell having a greater capacity and comprising a negative electrode consisting essentially of a support for the negative electrode active material and a positive electrode comprising a lithium oxide. Manganese substituted as positive electrode essential active material. According to the present invention, the above object can be achieved by a lithiated multicomponent metal oxide of formula Li2MbMn2.b04 prepared by contacting LiMbMn2_b04 with lithium suspended or dissolved in a solvent, where lithium generates solvated electrons or where it is present a catalyst capable of accepting a lithium electron and supplying it to the LiMbMn2.b04 reactant.

DESCRIPTION OF THE PREFERRED MODALITY As indicated above, this invention is directed to a method for the production of a lithiated multicomponent metal oxide, Li2MbMn2.b04. Specifically, said method is performed by providing LiMbMn2.b04, a lithium source, by dissolving lithium from the lithium source in a liquid medium wherein the lithium generates solvated electrons or the reduced form of an electron transfer catalyst and contacting the LiMbMn2.b04 with liquid medium containing lithium. The lithium source can be any source that provides elementary lithium available for the reaction. In accordance with the present invention, lithium is dissolved in a solvent in which the lithium generates solvated electrons or the reduced form of an electron transfer catalyst and the LiMbMn2.b04 is contacted with the dissolved lithium. Conveniently, the solvent is selected from the group consisting of ammonia, organic amines, ethers, pyridine, substituted pyridines, mixtures of ammonia and amines and mixtures of ammonia and ethers. Preferably, the solvent is ammonia, organic amines or pyridines. When the solvent is ammonia, the contacting step is conveniently carried out at a temperature of about -30 to -50 ° C. Preferably, the temperature during the contact stage is maintained at values of -33 to -45 ° C approximately. When ammonia is used as solvent, it is preferable that it be in liquid form. Optionally, the liquid medium of the present invention can be a solvent having an electron transfer catalyst dissolved therein. The liquid medium can also be a mixture of compounds that is liquid at the reaction temperature. Conveniently, when said liquid medium is employed, a catalyst selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone is added to the liquid medium. If the solvent used in the method of this invention is an organic amine, it is conveniently selected from the group consisting of methylamines, ethylamines, propylamines and butylamines. Conveniently, the method of this invention is carried out with the organic amine in the liquid state. Preferably, the contacting step of the present method is carried out at a temperature of about -25 to 100 ° C. Preferably, the contacting step is carried out at a temperature of about 20 to 90 ° C. If the solvent used in the method of this invention is a pyridine or a substituted pyridine, the contacting step is suitably carried out at a temperature of about -5 to 190 ° C. Preferably, when pyridine or a substituted pyridine is used as the solvent, the contacting step is carried out at a temperature of about 30 to 165 ° C. As indicated above, the use for which the Li2MbMn2.b04 prepared by the method of this invention can be uniquely applied is as a cathode for use in a secondary lithium ion electrochemical cell. Said stack may be of known design having a lithium intercalation anode, a suitable non-aqueous electrolyte, a cathode of material produced by the method of this invention and a separator between the anode and the cathode. The anode can be of any known material such as transition metal oxides, transition metal sulfides and carbonaceous materials. The non-aqueous electrolyte may be in the form of a liquid, a gel or a solid matrix containing mobile lithium ions. The lithiated multicomponent metal oxide is represented by the formula Li2MbMn2.b04 wherein M is a metal other than manganese and conveniently b is from 0.001 to about 1,999. Preferably, b is from 0.001 to 0.20 approximately. Suitably, the metal M is selected from the group consisting of Al, Ti, V, Cr, Fe, Co, Ni and Cu. Conveniently when the metal is Al, b is about 0.2 or less. Conveniently when the metal is Ti, b is about 0.2 or less. Conveniently when the metal is Cr, b is about 0.2 or less. Conveniently when the metal is Fe, b is about 0.5 or less. Conveniently when the metal is Co, b is about 0.2 or less. Conveniently when the metal is Ni, b is about 0.2 or less. Conveniently when the metal is Ni, b is about 0.5 or less. Conveniently when the metal is Ni, b is from about 0.5 to 1.99. Conveniently when the metal is Ni, b is about 1.10 or less. Conveniently when the metal is Cu, b is about 0.2 or less. Conveniently when the metal is V, b is about 0.2 or less. The process of the present invention can be optionally put into practice by providing an electron transfer catalyst to the suspension of LiMbMn2.b04 before or after the addition of lithium. Conveniently, the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. The products were analyzed by X-ray powder diffraction. Li2MbMn2.b04 materials tend to react with oxygen and water from the air. To avoid decomposition during X-ray analysis, the sample plates were prepared in an inert atmosphere box and a hydrocarbon oil (3-in-1 Household Oil ™) was mixed with the sample before pressing the plate. This procedure provided excellent protection. The formation of Li2MbMn2.b04 products was deduced from the presence of X-ray diffraction peaks close to those of the known compound Li2Mn204, as described in card 38-299 of the Powder Diffraction File described above. The results are offered in the Tables. Example 1 The experiments of Example 1 demonstrate the conversion of LiM02Mnx 804 to Li2M02Mnx 804 (M = Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in a liquid ammonia medium. In a Schlenk tube purged with argon 50 mmoles (approximately 9 g) of LiM02Mn1804 were charged and approximately 50 ml of liquid ammonia. Stirring was performed using a magnetically driven rod. Throughout the course of the experiment, a dry ice-acetone bath was periodically placed under the Schlenk tube to control the vaporization rate of the ammonia maintaining the temperature between the normal boiling point and about -40 ° C. The Schlenk tube was It was vented to the atmosphere through a bubbler filled with mineral oil, and in a dry saja approximately 0.35 g (50 mmoles) of lithium ribbon were cut into small pieces which were placed in a tightly capped Erlenmeyer flask. It was subsequently loaded into the Schlenk tube in a counter-flow of protective argon.The reaction was rapid.It immediately became evident the blue color of lithium dissolved in ammonia.In the space of less than 2 hours approximately, the blue color disappeared , all the lithium was consumed and the solid powder assumed a yellowish brown color, then the liquid ammonia was allowed to evaporate, the product further dried in a vacuum oil pump, while heat is supplied to the sample from several turns of electrical heating tape. The dried powder was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 1.

I Example 2 The experiments of Example 2 demonstrate the conversion of LiM02Mnx 804 to Li2M02Mn18O4 (M = Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in n-propylamine. In a Schlenk tube purged with argon 50 mmoles (approximately 0.9 g) of LiM02Mnx 804 and approximately 50 ml of n-propylamine were charged. The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath. The Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil. In a dry box, approximately 0.35 g (50 mmoles) of lithium ribbon were cut into small pieces which were placed in a tightly capped Erlenmeyer flask. The lithium was then charged to the Schlenk tube in a counterflow of protective argon. The reaction mixture was heated to maintain a slow reflux of n-propylamine in the air-cooled walls of the Schlenk tube (approximately 49 ° C). The reaction was relatively slow. In the course of approximately 24 hours, the lithium was consumed and the solid powder obtained assumed a yellowish brown color. The product was then recovered by filtration in a Schlenk filtration tube dried in an oven under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube and the tube was evacuated with an oil pump and heated with several turns of an electrical heating tape. The dried powder was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 2.

I t o I Example 3 The experiments of Example 3 demonstrate the conversion of LiM02Mnx 804 to Li2M0.MM ^ 804 (M = Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in pyridine. In a Schlenk tube purged with argon, 50 mmol (approximately 9 g) in LiM02Mnx 804 and approximately 50 ml of pyridine were charged. The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath. The Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil. In a dry box, approximately 0.35 g (50 mmoles) of lithium ribbon were shipped in small pieces which were placed in a tightly capped Erlenmeyer flask. The lithium was subsequently charged into the Schlenk tube in a counterflow of protective argon. The reaction mixture was heated to about 80 ° C. The reaction was rapid. In the course of about 1 hour, the lithium was consumed and the solid powder became yellowish brown. The product was then recovered by filtration in an oven-dried Schlenk filtration tube under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube and the tube was evacuated with an oil pump and heated with several turns of an electrical heating tape. The dried powder was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction, as described above. The results are shown in Table 3.

Item ? i Example 4 The experiments of Example 4 demonstrate the conversion of LiM02Mn1 # 8O4 to Li2M0 ¡M ^ 804 (M-Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in 1,2- diethoxyethane and pyridine. In a Schlenk tube purged with argon, 50 mmoles (approximately 9 g) of LiM02Mnx 804 were charged to approximately 40 ml of 1,2-diethoxyethane and approximately 10 ml of pyridine. The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath. The Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil. In a dry box, approximately 0.35 g (50 mmoles) of lithium ribbon were cut into small pieces which were placed in a tightly capped Erlenmeyer flask. The lithium was then charged to the Schlenk tube in a counterflow of protective argon. The reaction mixture was heated to about 110 ° C. The reaction was somewhat slower than for the corresponding reaction in pure pyridine. In about 4 hours, the lithium was consumed and the solid powder became yellowish brown. The product was then recovered by filtration in an oven-dried Schlenk filtration tube under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube and the tube was evacuated with an oil pump and heated with several turns of electrical heating tape. The dried powder was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 4.

Table 4 Preparation Experiments of Li2M0 2Mnx 804 in 1,2-Dietoxy-Ethane with pyridine catalyst t s.

Example 5 The experiments of Example 5 demonstrate the conversion of LiM02Mnj 804 to Li2M0? 2Mn?, ß ° 4 (M "A1» ti. V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in 1,2-diethoxyethane containing benzophenone as electron transfer catalyst. In a Schlenk tube purged with argon 50 mmoles (approximately 9 g) of LiM0 > 2Mnx, 804, approximately 50 ml of 1,2-diethoxyethane and approximately 0.5 g of benzophenone. The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath. The Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil. In a dry box, approximately 0.35 g (50 mmoles) of lithium ribbon were cut into small pieces which were placed in a tightly capped Erlenmeyer flask. The lithium was subsequently charged into the Schlenk tube in a counterflow of protective argon. The reaction mixture was heated to about 110 ° C. The reaction was somewhat slower than for the corresponding reaction where the catalyst was pyridine. In about 8 hours, the lithium was consumed and the solid powder became yellowish brown. The product was then recovered by filtration in a Schlenk filtration tube dried in an oven under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube, the tube being evacuated with an oil pump and then heated with several turns of electrical heating tape. The dried powder was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 5.

I tsJ Example 6 The experiments of Example 6 demonstrate the conversion of LiMor2Mnlr804 to Li2M0 # 2Mn1 < 804 (M = Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in 1, 2-diethoxyethane containing elemental sulfur as electron transfer catalyst. In a Schlenk tube purged with argon, 50 mmoles (approximately 9 g) of LiM02Mn1804, approximately 50 ml of 1,2-diethoxyethane and approximately 0.2 g of finely divided elemental sulfur were charged. The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath. The Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil. In a dry box, approximately 0.35 g (50 mmol) of lithium ribbon were cut into small pieces which were placed in a tightly capped Erlenmeyer flask. The lithium was subsequently charged into the Schlenk tube in a counter-flow of protective argon. The reaction mixture was heated to about 110 ° C. The reaction occurred uniformly for about 8 hours, at which time the lithium was consumed and the solid powder became yellowish brown. The product was then recovered by filtration in a Schlenk filtration tube dried in an oven under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube and the tube was evacuated with an oil pump and heated with several turns of an electrical heating tape. Sulfur was vaporized from the product during the drying step and collected in the coldest portions of the wall of the filter tube. The dry powder was easily separated from the sulfur, which remained adhered tightly to the wall. The product was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 6.

I? t i Example 7 The experiments of Example 7 demonstrate the conversion of LQ Q 2Mnx 804 to Li2M02Mn1804 (M = Al, Ti, V, Cr, Fe, Co, Ni and Cu) by reaction with elemental lithium in 1,2-diethoxyethane containing elemental iodine as electron transfer catalyst. In a Schlenk tube purged with argon, 50 mmoles (approximately 9 g of LiMo ^ M ^ 804, approximately 50 ml of 1,2-diethoxyethane and approximately 0.2 g of elemental iodine were charged.) The stirring was carried out using a magnetically driven rod. The heating was carried out using a thermostated oil bath, the Schlenk tube was vented to the atmosphere through a bubbler filled with mineral oil, and in a dry box about 0.35 g (50 mmol) of lithium ribbon were cut. in small pieces that were placed in a tightly capped Erlenmeyer flask, then the lithium was charged to the Schlenk tube in a counter-flow of protective argon.The reaction mixture was heated to approximately 110 ° C. The reaction occurred uniformly in about 8 hours, at which time the lithium was consumed and the solid powder became yellowish brown, then the product was recovered by filtration in a Schlen filtration tube K dried in oven under an argon atmosphere. The wet filter cake was washed in the frit with approximately 50 ml of tetrahydrofuran. Next, the surface dry filter cake was dried in the Schlenk filtration tube and the tube was evacuated with an oil pump and heated with several turns of electrical heating tape. The product was transferred to a glass jar in an inert atmosphere box and analyzed by X-ray powder diffraction as described above. The results are shown in Table 7. ? i

Claims (50)

1. CLAIMS 1.- A method for the preparation of Li2MbMn2.b04 / characterized in that it comprises the steps of: a. provide LiMbMn2.b04; b. provide a lithium source; c. providing a liquid medium wherein the lithium generates solvated electrons or the reduced form of an electron transfer catalyst; d. dissolving lithium from the lithium source in the liquid medium; and e. contact the LiMbMn2_b04 with the liquid medium containing the dissolved liquid and the solvated electrons or the reduced form of the electron transfer catalyst.
2. 2. A method according to claim 1, characterized in that the liquid medium is selected from the group consisting of ammonia, organic amines, ethers, pyridine, substituted pyridines, mixtures of ammonia and amines and mixtures of ammonia and ethers.
3. 3. A method according to claim 2, characterized in that the liquid medium is ammonia.
4. 4. A method according to claim 3, characterized in that the temperature during the contact stage is maintained between -30 and -50 ° C approximately. 5. - A method according to claim 4, characterized in that the temperature during the contact stage is maintained between -33 and -45"C approximately 6. - A method according to claim 2, character! - because the liquid medium is an amine 7. A method according to claim 6, characterized in that the contact step is carried out at a temperature between about -25 and 100 ° C. 8. A method according to claim 7, characterized in that the contact stage 9.- A method according to claim 6, characterized in that the organic amine is selected from the group consisting of methylamines, ethylamines, propylamines and butylamines. 6, characterized in that the organic amine is a liquid 11. A method according to claim 2, characterized in that the solvent is pyridine 12. A method according to claim 11, characterized because the contact stage is carried out at a temperature between -5 and 190 ° C approximately. 13. A method according to claim 12, characterized in that the contact stage is carried out at a temperature between about 35 and 125 ° C. 14. - A method according to claim 2, characterized in that the liquid medium is a substituted pyridine. 15. A method according to claim 14, characterized in that the contact stage is carried out at a temperature between approximately -5 and 190 ° C. 16. A method according to claim 15, characterized in that the contact stage is carried out at a temperature between about 35 and 165 ° C. 17. A method according to claim 2, characterized in that the liquid medium is a mixture of ammonia and amines. 18. A method according to claim 2, characterized in that the liquid medium is a mixture of ammonia and ethers. 19. A method according to claim 2, characterized in that the solvent is an ether. 20. A method according to claim 1, characterized in that it comprises the step of adding a catalyst to LiMbMn2.b04 before step (b). 21. A method according to claim 1, characterized in that it comprises the step of adding a catalyst to LiMbMn2.b04 before step (c). 22. A method according to claim 1, characterized in that it comprises the step of adding a catalyst to LiMbMn2.b04 immediately before step (d). 23. - A method according to claim 1, characterized in that it comprises the step of adding a catalyst to LiMbMn2.b04 immediately after step (d). 24. A method according to claim 20, characterized in that the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. 25. A method according to claim 21, characterized in that the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. 26. A method according to claim 22, characterized in that the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. 27. A method according to claim 23, characterized in that the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. 28. - A cathode for use in a secondary lithium ion electrochemical cell that is produced by the Li2MbMn2.b04 obtained by the method of claim 1. 29.- A secondary lithium ion electrochemical cell comprising a lithium intercalation anode, a suitable non-aqueous electrolyte, a cathode as defined in claim 28, and a separator between the anode and the cathode. 30. An electrochemical cell according to claim 29, characterized in that the anode comprises a material selected from the group consisting of transition metal oxides, transition metal sulfides and carbonaceous material, and because the electrolyte is in liquid form. 31.- A cathode for use in a secondary lithium ion electrochemical cell that is produced by the Li2MbMn2.b04 obtained by the method of claim 6. 32.- A secondary lithium ion electrochemical cell comprising a lithium intercalation anode , a suitable non-aqueous electrolyte, a cathode as defined in claim 31, and a separator between the anode and the cathode. 33. An electrochemical cell according to claim 32, characterized in that the anode comprises a material selected from the group consisting of transition metal oxides, transition metal sulfides and carbonaceous material, and because the electrolyte is in liquid form. 34. A method according to claim 1, characterized in that the liquid medium is a solvent having an electron transfer catalyst dissolved therein. 35. A method according to claim 34, characterized in that the liquid medium is a mixture of compounds that is in the liquid state at the reaction temperature. 36. A method according to claim 34, characterized in that the catalyst is selected from the group consisting of sulfur, sulfides, reducible sulfur compounds, iodine, iodides, reducible iodine compounds, pyridine, pyridine derivatives and benzophenone. 37. A method according to claim 1, characterized in that M is a metal other than manganese and b is from 0.001 to about 1,999. 38.- A method according to claim 37, characterized in that b is from 0.001 to 0.20 approximately. 39.- A method according to claim 37, characterized in that M is selected from the group consisting of Al, Ti, V, Cr, Fe, Co, Ni and Cu. 40. A method according to claim 39, characterized in that M is Al and b is 0.2 or less. 41. A method according to claim 39, characterized in that M is Ti and b is 0.2 or less. 42. A method according to claim 39, characterized in that M is Cr and b is 0.2 or less. 43.- A method according to claim 39, characterized in that M is Fe and b is 0.5 or less. 44. A method according to claim 39, characterized in that M is Co and b is 0.2 or less. 45. A method according to claim 39, characterized in that M is Ni and b is 0.2 or less. 46. A method according to claim 39, characterized in that M is Ni and b is 0.5 or less. 47. A method according to claim 39, characterized in that M is Ni and b is from about 0.5 to 1.99. 48. A method according to claim 39, characterized in that M is Ni and b is 1.10 or less. 49.- A method according to claim 39, characterized in that M is Cu and b is 0.2 or less. 50.- A method according to claim 39, characterized in that M is V and b is 0.2 or less.