Active metal/aqueous electrochemical cells and systems
Alkali (or other active) metal battery and other electrochemical cells incorporating active metal anodes together with aqueous cathode/electrolyte systems. The battery cells have a highly ionically conductive protective membrane adjacent to the alkali metal anode that effectively isolates (de-couples) the alkali metal electrode from solvent, electrolyte processing and/or cathode environments, and at the same time allows ion transport in and out of these environments. Isolation of the anode from other components of a battery cell or other electrochemical cell in this way allows the use of virtually any solvent, electrolyte and/or cathode material in conjunction with the anode. Also, optimization of electrolytes or cathode-side solvent systems may be done without impacting anode stability or performance. In particular, Li/water, Li/air and Li/metal hydride cells, components, configurations and fabrication techniques are provided.
1. A battery cell, comprising:
an active metal anode comprising lithium having a first surface and a second surface;
a cathode structure comprising an electronically conductive component, an ionically conductive component, and an electrochemically active component, wherein at least one cathode structure component comprises an aqueous constituent;
an ionically conductive protective membrane on the first surface of the anode, the membrane comprising,
a first material component in contact with the anode that is ionically conductive and chemically compatible with lithium, the first material component comprising a material selected from the group consisting of a composite reaction product of lithium with a Cu 3 N, a composite reaction product of lithium with PbI 2 , and a reaction product of lithium with red phosphorus, and
a second material component in contact with the first material component, the second material being substantially impervious, ionically conductive and chemically compatible with the first material component and the cathode structure, the second material component selected from the group consisting of ceramic active metal ion conductors and glass-ceramic active metal ion conductors.
2. The cell of claim 1 , wherein the cathode structure comprises an aqueous electrochemically active component.
3. The cell of claim 2 , wherein the aqueous electrochemically active component is water.
4. The cell of claim 1 , wherein the ionically conductive component and the electrochemically active component are comprised of an aqueous electrolyte.
5. The cell of claim 4 , wherein the aqueous electrolyte is selected from the group consisting of strong acid solutions, weak acid solutions, basic solutions, neutral solutions, amphoteric solutions, peroxide solutions and combinations thereof.
6. The cell of claim 4 , wherein the aqueous electrolyte comprises members selected from the group consisting of aqueous solutions of HCl, H 2 SO 4 , H 3 PO 4 acetic acid/Li acetate, LiOH; sea water, LiCl, LiBr, LiI, NH 4 Cl, NH 4 Br and hydrogen peroxide, and combinations thereof.
7. The cell of claim 6 , wherein the aqueous electrolyte is sea water.
8. The cell of claim 6 , wherein the aqueous electrolyte comprises sea water and hydrogen peroxide.
9. The cell of claim 2 , wherein the cathode structure electronically conductive component is a porous catalytic support.
10. The cell of claim 9 , wherein the porous catalytic electronically conductive support is reinforced.
11. The cell of claim 9 , wherein the porous catalytic electronically conductive support comprises nickel.
12. The cell of claim 9 , wherein the porous catalytic electronically conductive support comprises an inert material impregnated with a water reducing catalyst.
13. The cell of claim 9 , wherein the porous catalytic electronically conductive support is treated with an ionomer.
14. The cell of claim 2 , wherein the cell has an open cell voltage of at least 2 V.
15. The cell of claim 8 , wherein the cell has a flat discharge potential of at least 3.5 V.
16. The cell of claim 1 , further comprising a PEM H 2 /O 2 fuel cell to capture hydrogen released from the cathode structure in the battery cell redox reaction.
17. The cell of claim 1 , wherein the active metal is lithium.
18. The cell of claim 17 , wherein wherein the cathode structure comprises an aqueous electrochemically active component.
19. The cell of claim 1 , wherein the ionic conductivity of the protective membrane is at least 10 −7 S/cm.
20. The cell of claim 1 , wherein the ionic conductivity of the protective membrane is at least 10 −5 S/cm.
21. The cell of claim 1 , wherein the protective composite is a laminate.
22. The cell of claim 1 , wherein the protective composite is graded.
23. The cell of claim 1 , wherein the active metal of the negative electrode is lithium or a lithium alloy.
24. The cell of claim 1 , wherein the first component comprises a material selected from the group consisting of a reaction product of lithium with red phosphorus.
25. The cell of claim 1 , wherein the first layer comprises a material selected from the group consisting of a composite reaction product of Li with Cu 3 N.
26. The cell of claim 1 , wherein the second component is a glass-ceramic active metal ion conductor.
27. The cell of claim 26 , wherein the second component is an ion conductive glass-ceramic having the following composition:
Composition
mol %
P 2 O 5
26-55%
SiO 2
0-15%
GeO 2 + TiO 2
25-50%
in which
GeO 2
0-50%
TiO 2
0-50%
ZrO 2
0-10%
M 2 O 3
0 < 10%
Al 2 O 3
0-15%
Ga 2 O 3
0-15%
Li 2 O
3-25%
and containing a predominant crystalline phase composed of Li 1+x (M,Al,Ga) x (Ge 1−y Ti y ) 2−x (PO 4 ) 3 where X≦0.8 and 0≦Y≦1.0, and where M is an element selected from the group consisting of Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb and/or and Li 1+x+y Q x Ti 2−x Si y P 3−y O 12 where 0<X≦0.4 and 0<Y≦0.6, and where Q is Al or Ga.
28. The cell of claim 1 , wherein the cell is a primary cell.
29. The cell of claim 1 , wherein the cell is a rechargeable cell.
30. The cell of claim 1 , wherein the cell has a planar configuration.
31. The cell of claim 30 , wherein the cell is bonded into a flexible array of like cells by elastomeric seals.
32. The cell of claim 1 , wherein the cell has a tubular configuration.
33. The cell of claim 1 , wherein the cell comprise a capillary construction.