ELECTRODE STRUCTURES AND SURFACES FOR Li BATTERIES

Abstract

This invention relates to positive electrode materials for electrochemical cells and batteries. It relates, in particular, to electrode precursor materials comprising manganese ions and to methods for fabricating lithium-metal-oxide electrode materials and structures using the precursor materials, notably for lithium cells and batteries. More specifically, the invention relates to lithium-metal-oxide electrode materials with layered-type structures, spinel-type structures, combinations thereof and modifications thereof, notably those with imperfections, such as stacking faults and dislocations. The invention extends to include lithium-metal-oxide electrode materials with modified surfaces to protect the electrode materials from highly oxidizing potentials in the cells and from other undesirable effects, such as electrolyte oxidation, oxygen loss and/or dissolution.

1 . A positive electrode for an electrochemical cell, the electrode being formed by a method comprising:
 (a) contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material;   (b) heat-treating the resulting product to form a powdered metal oxide composition; and   (c) forming an electrode from the powdered metal oxide composition;   wherein the powdered metal oxide composition has a layered-type structure, a spinel-type structure, a rock salt-type structure, or an integrated structure comprising one or more of these structure types.   
     
     
         2 . The positive electrode of  claim 1  in which the hydrogen-lithium-manganese-oxide material comprises hydrogen, lithium, manganese, and oxygen ions, and the oxygen ions are arranged in alternating layers of octahedra and trigonal prisms in the crystal structure of the material. 
     
     
         3 . The positive electrode of  claim 1  wherein the hydrogen-lithium-manganese-oxide material in step (a) is formed by contacting a lithium-manganese-oxide precursor compound with a solution comprising an acid and the one or more metal ions, and the one or more metal ions are inserted into the hydrogen-lithium-manganese-oxide material during the formation thereof; wherein the precursor compound comprises lithium, manganese, and oxygen ions in a layered-type structure wherein lithium ions occupy octahedral sites in lithium-rich layers, and the lithium and manganese ions occupy octahedral sites in manganese-rich layers that alternate with the lithium-rich layers. 
     
     
         4 . The positive electrode of  claim 3  wherein the electrode contains cation or anion defects and/or stacking faults and dislocations. 
     
     
         5 . The positive electrode of  claim 3  wherein the precursor compound comprises Li 2 MnO 3  or Li[Li 1/3 Mn 2/3 ]O 2 , and optionally includes up to 25 atom percent of one or more other metal ions. 
     
     
         6 . The positive electrode of  claim 3  wherein the solution comprising the acid and the one or more metal ions also includes one or more metalloid-containing ions, non-metal containing ions, or a combination thereof. 
     
     
         7 . The positive electrode of  claim 1  wherein the manganese and non-lithium metal ions are partially disordered between lithium-rich layers and manganese-rich layers. 
     
     
         8 . The positive electrode of  claim 1  wherein the one or more metal ions are selected from the group consisting of an alkali metal ion, an alkaline earth metal ion, and a transition metal ion. 
     
     
         9 . The positive electrode of  claim 1  wherein a surface of the electrode, the individual particles of the powdered metal oxide composition, or both, comprises a coating that includes at least one material selected from the group consisting of a metal oxide, a metal fluoride, and a metal polyanionic material. 
     
     
         10 . The positive electrode of  claim 9  wherein the coating comprises at least one material selected from the group consisting of (a) lithium fluoride, (b) aluminum fluoride, (c) a lithium-metal-oxide in which the metal is selected from the group consisting of Al and Zr, (d) a lithium-metal-phosphate in which the metal is selected from the group consisting of Fe, Mn, Co, and Ni, and (e) a lithium-metal-silicate comprising a metal selected from the group comprising Al and Zr. 
     
     
         11 . The positive electrode of  claim 1  wherein the hydrogen-lithium-manganese-oxide material also includes up to 25 atom percent of one or more other transition metal ions replacing manganese ions, lithium ions, or a combination thereof in a manganese-rich layer of the material. 
     
     
         12 . The positive electrode of  claim 11  wherein the one or more other transition metal ions comprises a Ti ion, a Zr ion, a Co ion, a Ni ion, or a combination thereof. 
     
     
         13 . The positive electrode of  claim 3  wherein the precursor compound is prepared by the reaction of one or more lithium salts, one or more manganese salts, and optionally one or more other metal salts at elevated temperature in air. 
     
     
         14 . The positive electrode of  claim 13  wherein the salts are selected from the group consisting of carbonates, hydroxides, nitrates, and isopropoxides. 
     
     
         15 . The positive electrode of  claim 13  wherein the elevated temperature is in the range of about 450 to about 550° C. 
     
     
         16 . A positive electrode for an electrochemical cell, the electrode comprising a composite electrode structure containing Li 2 MnO 3  and MO components in which M comprises one or more metal cations. 
     
     
         17 . The positive electrode of  claim 16  wherein M comprises one or more of Ti, Mn, Fe, Co and Ni. 
     
     
         18 . The positive electrode of  claim 16  wherein the MO component has the formula Li x M′ 1−x O in which 0<x<0.5 and M′ comprises one or more metal ions other than lithium. 
     
     
         19 . The positive electrode of  claim 16  wherein the MO component has the formula Li x−y M′ 1−x O in which 0<x<0.5 and M′ comprises one or more metal ions other than lithium, and y≦x. 
     
     
         20 . The positive electrode of  claim 16  wherein the Li 2 MnO 3  and MO components are integrated with or combined with one or more other components having a spinel-type structure, a layered-type structure, or both. 
     
     
         21 . The positive electrode of  claim 20  wherein the Li 2 MnO 3  and MO components have disordered or partially disordered structures, and optionally include stacking faults, dislocations, or a combination thereof. 
     
     
         22 . The positive electrode of  claim 16  wherein a surface of the electrode, the individual particles of the powdered metal oxide composition, or both, comprises a coating that includes at least one material selected from the group consisting of a metal oxide, a metal fluoride, and a metal polyanionic material. 
     
     
         23 . The positive electrode of  claim 22  wherein the coating comprises at least one material selected from the group consisting of (a) lithium fluoride, (b) aluminum fluoride, (c) a lithium-metal-oxide in which the metal is selected from the group consisting of Al and Zr, (d) a lithium-metal-phosphate in which the metal is selected from the group consisting of Fe, Mn, Co, and Ni, and (e) a lithium-metal-silicate comprising a metal selected from the group comprising Al and Zr. 
     
     
         24 . An electrochemical cell comprising the positive electrode of  claim 16 , a negative electrode, and a lithium containing an electrolyte therebetween, and the negative electrode optionally comprises a metal selected from the group consisting of lithium, sodium, magnesium, zinc, and aluminum. 
     
     
         25 . A battery comprising a plurality of electrochemical cells of  claim 24  arranged in parallel, in series, or both. 
     
     
         26 . An electrochemical cell comprising the positive electrode of  claim 1 , a negative electrode, and a lithium containing an electrolyte therebetween, and the negative electrode optionally comprises a metal selected from the group consisting of lithium, sodium, magnesium, zinc, and aluminum. 
     
     
         27 . A battery comprising a plurality of electrochemical cells of  claim 26  arranged in parallel, in series, or both. 
     
     
         28 . A method for fabricating a positive electrode comprising:
 (a) contacting a hydrogen-lithium-manganese-oxide material with one or more metal ions to insert the one or more metal ions into the hydrogen-lithium-manganese-oxide material; wherein the one or more metal ions optionally comprises manganese and nickel in combination with lithium ions.   (b) heat-treating the resulting product to form a powdered metal oxide composition; and   (c) forming an electrode from the powdered metal oxide composition.   
     
     
         29 . The method of  claim 28  wherein the hydrogen-lithium-manganese-oxide material in step (a) is formed by contacting a lithium-manganese-oxide precursor compound with a solution comprising an acid and the one or more metal ions, and the one or more metal ions are inserted into the hydrogen-lithium-manganese-oxide material during the formation thereof; wherein the precursor compound comprises lithium, manganese, and oxygen ions in a layered-type structure wherein lithium ions occupy octahedral sites in lithium-rich layers, and the lithium and manganese ions occupy octahedral sites in manganese-rich layers that alternate with the lithium-rich layers. 
     
     
         30 . A positive electrode formed by the method of  claim 28 . 
     
     
         31 . An electrochemical cell comprising the positive electrode of  claim 30 , a negative electrode, and a lithium containing electrolyte therebetween, 
     
     
         32 . A battery comprising a plurality of electrochemical cells of  claim 31  arranged in parallel, in series, or both.