Electrochemical cell

Claim 2

An electrochemical cell precursor which comprises: a cell housing; an anode terminal exposed to the interior of the cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a cathode precursor located in the cell housing, the cathode precursor comprising at least one chemically produced compound of lithium, manganese and oxygen, the cathode precursor being electronically insulated from the anode terminal and being electrochemically coupled to the anode terminal by the electrolyte, and each said chemically produced compound having a composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 3

A cell precursor as claimed in claim 1, in which said composition falls within the area of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 7 Mn 5 O 12 tie line and the Li 7 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 4

A precursor as claimed in claim 2, in which said composition falls within the area of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 MnO 2 tie line, the Li 2 MnO 2 -LiMnO 2 tie line, the LiMnO 2 -Li 7 Mn 5 O 12 tie line and the Li 7 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 5

A precursor as claimed in claim 1, in which there is an anode in the cell housing, the anode being electronically connected to the anode terminal and being selected from the group consisting of lithium metal, lithium/aluminium alloys, lithium/silicon alloys, lithium/carbon compunds and mixtures thereof, the electrolyte being selected from the group consisting of LiClO 4 , LiAsF 6 , LiBF 4 and mixtures thereof, dissolved in a solvent selected from the group consisting of propylene carbonate, dimethoxy ethane and mixtures thereof, and the anode being separated from the cathode by a microporous separator of electronically insulating material which is permeable by and impregnated by the electrolyte.

Claim 8

A method as claimed in claim 5, which includes the step of producing the cathode precursor by heating, in a reducing environment, a substance comprising at least one compound of lithium, manganese and oxygen to a temperature of 80°-800° C. for a period of 3-72 hours, to remove oxygen therefrom.

Claim 9

A method as claimed in claim 6, in which the heating is in a reducing atmosphere selected from hydrogen and hydrogen/inert gas mixtures, being to a temperature of 250°-400° C. for a period of 12-48 hours, the substance having an average composition which, with reference to said isothermal slice of the Li-Mn-O phase diagram at 20° C., falls within the area of the triangle whose boundary is defined by the MnO-MnO 2 tie line, the MnO 2 -Li 2 MnO 3 tie line, and the Li 2 MnO 3 -MnO tie line.

Claim 10

A method as claimed in claim 6, which includes the step of making said substance which is subject to reduction by initially mixing together a lithium-containing component selected from lithium salts, lithium oxides, lithium hydroxides and mixtures thereof, with a manganese-containing compound selected from manganese salts, manganese oxides, manganese hydroxides, lithium manganese oxides and mixtures thereof.

Claim 11

An electrochemical cell precursor, produced by the method of claim 5.

Claim 12

A method of making an electrochemical cell and electrodes for such cell, the method comprising subjecting an electrochemical cell precursor as claimed in claim 1 to a charging potential which causes the cathode precursor to act as a cathode, so that the cathode precursor becomes delithiated and activated by removal of lithium ions therefrom, which ions migrate towards the anode terminal, lithium being deposited to form at least part of an anode for the cell, the charging potential being applied until the average composition of the cathode precursor is at a position on the isothermal slice of the Li-Mn-O phase diagram at 20° C. which is no closer to the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line than the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line.

Claim 13

A method as claimed in claim 10, in which the charging potential is applied until the average composition of the cathode precursor reaches a position on said slice which is further from the Li 14 Mn 5 O 12 -Li 2 -Mn 3 O 4 tie line than the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line, the cell being discharged so that said average composition falls on the LiMn 3 O 4 -Li 7 Mn 5 O 12 tie line.

Claim 14

A method as claimed in claim 10, in which the cell precursor has been produced by the method of loading into a cell housing having an anode terminal, an electrolyte and a cathode precursor, such that the anode terminal is electrochemically coupled by the electrolyte to the cathode precursor and is electronically insulated from the cathode precursor, the cathode precursor comprising at least one chemically produced compound of lithium, manganese and oxygen, each said chemically produced compound having a composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 15

An electrochemical cell, produced by the method of claim 10.

Claim 16

An electrode for an electrochemical cell, produced by the method of claim 10.

Claim 17

A cathodic electrode, produced by the method of claim 10.

Claim 18

An electrochemical cell precursor which comprises: a cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a chemically produced cathode precursor located in the cell housing, the cathode precursor having an average composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line, at least 50 mole % of the cathode precursor comprising at least one chemically produced electrochemically active compound of lithium, manganese and oxygen which also has a composition which, with reference to said slice, falls inside the boundary of said quadrilateral, the housing, electrolyte and cathode precursor being arranged to permit a charging potential to be applied to the cell precursor to cause lithium from the cathode precursor to form, in the cell housing, at least part of an anode, while converting the cathode precursor to a cathode coupled electrochemically by the electrolyte to the anode.

Claim 19

An electrochemical cell precursor which comprises: a cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a chemically produced cathode precursor located in the cell housing, the cathode precursor having an average composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line, at least 50 mole % of the cathode precursor comprising at least one chemically produced electrochemically active compound of lithium, manganese and oxygen which also has a composition which, with reference to said slice, falls inside the boundary of said quadrilateral, the housing, electrolyte and cathode precursor being arranged to permit a charging potential to be applied to the cell precursor to cause lithium from the cathode precursor to form, in the cell housing, at least part of an anode, while converting the cathode precursor to a cathode coupled electrochemically by the electrolyte to the anode.

Claim 20

A cell precursor as claimed in claim 16, in which each said composition falls within the area of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 7 Mn 5 O 12 tie line and the Li 7 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 21

A cell precursor as claimed in claim 16, in which each said composition falls within the area of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 MnO 2 tie line, the Li 2 MnO 2 -LiMnO 2 tie line, the LiMnO 2 -Li 7 Mn 5 O 12 tie line and the Li 7 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line.

Claim 22

A cell precursor as claimed in claim 16, in which there is an anode containing electrochemically active lithium in the cell housing, the anode comprising a lithium-containing substance selected from the group consisting of lithium metal, lithium/aluminum alloys, lithium/silicon alloys, lithium/carbon compounds and mixtures thereof, the electrolyte being selected from the group consisting of LiClO 4 , LiAsF 6 , LiBF 4 and mixtures thereof, dissolved in a solvent selected from the group consisting of polypropylene carbonate, dimethoxy ethane and mixtures thereof, and the anode being separated from the cathode precursor by a microporous separator of electronically insulating material which is permeable by and impregnated by the electrolyte.

Claim 25

A method as claimed in claim 10, in which the cell precursor which is subjected to the charging potential is a cell precursor which comprises: a cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a chemically produced cathode precursor located in the cell housing, the cathode precursor having an average composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 14 Mn 5 O 12 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -Li 14 Mn 5 O 12 tie line, at least 50 mole % of the cathode precursor comprising at least one chemically produced electrochemically active compound of lithium, manganese and oxygen which also has a composition which, with reference to said slice, falls inside the boundary of said quadrilateral, the housing, electrolyte and cathode precursor being arranged to permit a charging potential to be applied to the cell precursor to cause lithium from the cathode precursor to form, in the cell housing, at least part of an anode, while converting the cathode precursor to a cathode coupled electrochemically by the electrolyte to the anode.

Claim 26

A cell precursor as claimed in claim 16, in which there is no electrochemically active lithium which is located in the housing and forms part of an anode.

Claim 27

A cell precursor as claimed in claim 16, in which the cathode precursor comprises, in addition to said electrochemically active compound, at least one diluent lithium manganese oxide compound, the diluent compound having a composition, which, with reference to said slice, falls within the triangle whose boundary is defined by the LiMn 3 O 4 -MnO 2 tie line, the MnO 2 -Li 4 Mn 5 O 12 tie line and the Li 4 Mn 5 O 12 -LiMn 3 O 4 tie line.

Claim 28

An electrochemical cell precursor which comprises: a cell housing; an anode terminal exposed to the interior of the cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a chemically produced cathode precursor located in the cell housing, the cathode precursor comprising at least one compound of lithium, manganese and oxygen, the cathode precursor being electronically insulated from the anode terminal and being electrochemically coupled to the anode terminal by the electrolyte, and each said chemically produced compound having a composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 2 MnO 2 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -LiMnO 2 tie line and the LiMnO 2 -Li 2 MnO 2 tie line.

Claim 29

An electrochemical cell precursor which comprises: a cell housing; an anode terminal exposed to the interior of the cell housing; an electrolyte located in the cell housing for electrochemically coupling an anode to a cathode in the cell housing; and a chemically produced cathode precursor located in the cell housing, the cathode precursor comprising at least one compound of lithium, manganese and oxygen, the cathode precursor being electronically insulated from the anode terminal and being electrochemically coupled to the anode terminal by the electrolyte, and each said chemically produced compound having a composition which, with reference to an isothermal slice of the Li-Mn-O phase diagram at 20° C., falls inside the boundary of the quadrilateral whose boundary is defined by the Li 2 MnO 2 -Li 2 Mn 3 O 4 tie line, the Li 2 Mn 3 O 4 -LiMn 3 O 4 tie line, the LiMn 3 O 4 -LiMnO 2 tie line and the LiMnO 2 -Li 2 MnO 2 tie line.

Claim 32

A method as claimed in claim 25, in which chemically producing the the cathode precursor includes mixing together said components to form a mixture, and heating the mixture.

Claim 33

A method as claimed in claim 26, in which the heating of the mixture is in a non-reducing environment, to a temperature of 350°-950° C. for a period of 5-6 hours, to produce a substance comprising at least one compound of lithium, manganese and oxygen, the heating thereafter being of said substance in a reducing environment to a temperature of 80°-800° C. for a period of 3-72 hours, to remove oxygen therefrom.