Manganese oxide composite electrodes for lithium batteries
An activated electrode for a non-aqueous electrochemical cell is disclosed with a precursor thereof a lithium metal oxide with the formula x{zLi 2 MnO 3 .(1−z)LiM′O 2 }.(1−x)LiMn 2−y M y O 4 for 0<x<1; 0≦y≦0.5; and 0<z<1, comprised of layered zLi 2 MnO 3 .(1−z)LiM′O 2 and spinel LiMn 2−y M y O 4 components, physically mixed or blended with one another or separated from one another in a compartmentalized electrode, in which M is one or more metal ions, and in which M′ is selected from one or more first-row transition metal ions, The electrode is activated by removing lithium and lithia, from the precursor. A cell and battery are also disclosed incorporating the disclosed positive electrode.
1. An activated electrode for a non-aqueous electrochemical cell, having as a precursor thereof a lithium metal oxide with the formula xLi 2 MnO 3 .(1−x)LiMn 2−y M y O 4 for 0.5<x<1.0 such that the spinel component constitutes less than 50 mole % of the precursor electrode and 0≦y<1 in which the Li 2 MnO 3 and LiMn 2−y M y O 4 components have layered and spinel-type structures, respectively, and in which M is one or more metal cations, said activated electrode being activated by removing lithia, or lithium and lithia, from said precursor, wherein the Li 2 MnO 3 component of the electrode precursor is replaced by a layered xLi 2 MnO 3 .(1−x)LiM′O 2 component in which M′ is selected from one or more first-row transition metal ions and 0<x<1.
2. An activated electrode according to claim 1 , wherein the spinel component is an end-of-charge indicator and/or an end-of-discharge indicator.
3. An activated electrode according to claim 1 , in which the spinel component constitutes less than 20 mole % of the precursor electrode.
4. An activated electrode according to claim 3 , in which the spinel component constitutes less than 10 mole % of the precursor electrode.
5. An activated electrode according to claim 1 , in which M is one or more monovalent, divalent, trivalent or tetravalent cations.
6. An activated electrode according to claim 1 , in which M′ is selected from Mn, Co and Ni ions.
7. An activated electrode according to claim 1 , in which M′ is replaced by 10% or less of Li, Mg and/or Al ions.
8. An activated electrode according to claim 1 , in which the individual components of the electrode are either physically mixed with one another, or separated from one another in a compartmentalized electrode.
9. An activated electrode for a non-aqueous electrochemical cell, having as a precursor thereof a lithium metal oxide with the formula xLi 2 MnO 3 .(1−x)LiMn 2−y M y O 4 for 0.5<x<1.0 and 0≦y<1 in which the Li 2 MnO 3 and LiMn 2−y M y O 4 components have layered and spinel-type structures, respectively, and in which M is one or more metal cations, said activated electrode being activated by removing lithia, or lithium and lithia, from said precursor, wherein either the Li 2 MnO 3 or LiMn 2−y M y O 4 component of the electrode precursor is replaced by a Li 2 O.zMnO 2 component that does not have a layered- or a spinel-type structure such that the spinel component constitutes less than 50 mole % of the precursor electrode.
10. An activated electrode according to claim 9 wherein the spinel component is used as an end-of-charge indicator and/or an end-of-discharge indicator.
11. An activated electrode according to claim 9 , in which the components are partially reduced to provide mixed Mn 4+/3+ valence in the precursor electrode.
12. An activated electrode according to claim 9 , in which the electrode precursor is activated electrochemically.
13. An activated electrode according to claim 9 , in which the electrode precursor is activated chemically with acid.
14. An electrochemical cell comprising an activated electrode of claim 1 , and further including a negative electrode, and an electrolyte, wherein said Li 2 MnO 3 component of the positive electrode precursor is replaced by a layered xLi 2 MnO 3 .(1−x)LiM′O 2 component in which M′ is selected from one or more first-row transition metal ions and 0<x<1, thereby forming an electrochemical cell.
15. An electrochemical cell comprising an activated electrode of claim 9 , and further including a negative electrode, and an electrolyte, wherein either the Li 2 MnO 3 or LiMn 2−y M y O 4 component of the positive electrode precursor is replaced by a Li 2 O.zMnO 2 component that does not have a layered- or a spinel-type structure, thereby forming an electrochemical cell.
16. A plurality of electrochemical cells of claim 14 arranged in parallel and/or in series to form a battery.
17. A plurality of electrochemical cells of claim 15 arranged in parallel and/or in series to form a battery.