Separation of electrolytes
Methods and articles relating to separation of electrolyte compositions within lithium batteries are provided. Suitable electrolytes for the lithium batteries can comprise a heterogeneous electrolyte including a first electrolyte solvent (e.g., dioxolane (DOL)) that partitions towards the anode and is favorable towards the anode (e.g., as an “anode-side electrolyte solvent”) and a second electrolyte solvent (e.g., 1,2-dimethoxyethane (DME)) that partitions towards the cathode and is favorable towards the cathode (e.g., an “cathode-side electrolyte solvent”). By separating the electrolyte solvents during operation of the battery such that the anode-side electrolyte solvent is present disproportionately at the anode and the cathode-side electrolyte solvent is present disproportionately at the cathode, the battery can benefit from desirable characteristics of both electrolyte solvents (e.g., relatively low lithium reactivity of the anode-side electrolyte solvent and relatively high polysulfide solubility of the cathode-side electrolyte solvent).
1. A lithium battery, comprising:
an anode comprising lithium as an electroactive species;
a cathode comprising an electroactive species, wherein the electroactive species is adjacent a cathode current collector; and
a heterogeneous electrolyte between the anode and the cathode current collector, comprising a first electrolyte solvent comprising 1, 3-dioxolane and a second electrolyte solvent comprising dimethoxyethane, wherein at least a portion of the first electrolyte solvent is present disproportionately in a layer adjacent the anode at a molar or weight ratio of at least 2:1 relative to the second electrolyte solvent, and at least a portion of the second electrolyte solvent is present disproportionately within the cathode at a molar or weight ratio of at least 2:1 relative to the first electrolyte solvent.
2. A lithium battery as in claim 1 , wherein the anode comprises lithium metal as the electroactive species.
3. A lithium battery as in claim 1 , wherein the anode comprises a lithium alloy as the electroactive species.
4. A lithium battery as in claim 1 , wherein the anode comprises a lithium intercalation compound as the electroactive species.
5. A lithium battery as in claim 1 , wherein the second electrolyte solvent is essentially free of contact with the anode.
6. A lithium battery as in claim 1 , wherein the first and/or second electrolyte solvents contain lithium salts.
7. A lithium battery as in claim 1 , wherein the layer adjacent the anode is a polymer gel layer, wherein in use, the polymer gel layer disproportionately contains the first electrolyte solvent, and the second electrolyte solvent is present disproportionately in a region between the polymer gel layer and the cathode current collector.
8. A lithium battery as in claim 7 , wherein the cathode comprises sulfur as the electroactive species, and the second electrolyte solvent contains polysulfide species to a greater extent than the first electrolyte solvent.
9. A lithium battery as in claim 7 , wherein the polymer gel layer is in contact with the lithium.
10. A lithium battery as in claim 7 , wherein the polymer gel layer is in contact with an anode protective layer.
11. A lithium battery as in claim 7 , wherein a ratio of polysulfide solubility between the second electrolyte solvent and the first electrolyte solvent is greater than 2:1.
12. A lithium battery as in claim 7 , wherein the polymer gel layer has a thickness of between 10 to 30 microns.
13. A lithium battery as in claim 7 , wherein the polymer gel layer has a thickness of between 5 to 10 microns.
14. A lithium battery as in claim 7 , comprising at least one protective layer adjacent the anode, wherein the at least one protective layer is positioned between the anode and the polymer gel layer.
15. A lithium battery as in claim 14 , wherein the at least one protective layer is an ion conducting layer that is conductive to lithium ions.
16. A lithium battery as in claim 7 , wherein the polymer gel layer is directly adjacent the anode.
17. A lithium battery as in claim 7 , wherein the polymer gel layer comprises a copolymer.
18. A lithium battery as in claim 17 , wherein the polymer gel layer comprises a polyvinylidene fluoride-hexafluoropropylene copolymer.
19. A lithium battery as in claim 1 , wherein the first electrolyte solvent is essentially free of polysulfide species.
20. A lithium battery as in claim 1 , wherein the lithium battery further comprises a component positioned between the anode and the cathode current collector, wherein the component has a higher affinity for the second electrolyte solvent than the first electrolyte solvent.
21. A lithium battery as in claim 20 , wherein the component is a separator that disproportionately contains the second electrolyte solvent at a molar or weight ratio of at least 2:1 relative to the first electrolyte solvent.
22. A lithium battery as in claim 20 , wherein the component comprises a polymeric material that is formed as a layer adjacent the cathode.
23. A lithium battery as in claim 20 , wherein the component that has a higher affinity for the second electrolyte solvent than the first electrolyte solvent is a polymer layer in contact with the cathode.
24. A lithium battery as in claim 23 , wherein the polymer layer is positioned on the cathode.
25. A lithium battery as in claim 20 , wherein the component that has a higher affinity for the second electrolyte solvent than the first electrolyte solvent is a polymeric material dispersed in the cathode.
26. A lithium battery as in claim 20 , wherein the component that has a higher affinity for the second electrolyte solvent than the first electrolyte solvent is a separator.
27. A lithium battery as in claim 1 , wherein a ratio of wt % Li depletion per duty cycle of the first electrolyte solvent to the wt % Li depletion per duty cycle of the second electrolyte solvent is less than 0.2:1.
28. A lithium battery as in claim 1 , wherein the first and second electrolyte solvents are immiscible.
29. A lithium battery as in claim 28 , wherein the first and second electrolyte solvents are miscible before, but immiscible after, commencement of a first discharge.
30. A lithium battery as in claim 1 , wherein the cathode comprises a polymeric material that is dispersed in the cathode, and wherein the cathode has a higher affinity for the second electrolyte solvent than the first electrolyte solvent.
31. A lithium battery as in claim 1 , further comprising a separator positioned between the anode and the cathode.
32. A lithium battery as in claim 1 , further comprising a polymer layer in contact with the anode or cathode.
33. A lithium battery as in claim 32 , wherein the polymer layer in contact with the anode or cathode comprises a heterogeneous insoluble filler.
34. A lithium battery as in claim 33 , wherein the heterogeneous insoluble filler comprises a metal oxide, an oxy-hydroxide, a sulfide, a nitride, or a combination thereof.
35. A lithium battery as in claim 33 , wherein the heterogeneous insoluble filler comprises Al 2 O 3 , AlOOH, SiO 2 , AlN, BN, or Li 3 N.
36. A lithium battery as in claim 32 , wherein the polymer layer in contact with the anode comprises more than one polymer layer coated in sequence.
37. A lithium battery as in claim 1 , wherein the electrolyte comprises lithium nitrate.
38. A method, comprising:
in a lithium battery comprising:
an anode comprising lithium as an electroactive species;
a cathode comprising an electroactive species, wherein the electroactive species is adjacent a cathode current collector; and
a heterogeneous electrolyte between the anode and the cathode current collector, comprising a first electrolyte solvent comprising 1, 3-dioxolane and a second electrolyte solvent comprising dimethoxyethane, performing the step of:
discharging and/or charging the lithium battery, wherein during at least a portion of the discharge and/or charge, at least a portion of the first electrolyte solvent is present disproportionately in a layer adjacent the anode at a molar or weight ratio of at least 2:1 relative to the second electrolyte solvent, and at least a portion of the second electrolyte solvent is present disproportionately within the cathode at a molar or weight ratio of at least 2:1 relative to the first electrolyte solvent.
39. A lithium battery, comprising:
an anode comprising lithium as an electroactive species;
a cathode comprising an electroactive species, wherein the electroactive species of the cathode is adjacent a cathode current collector;
a polymer gel layer adjacent the anode; and
a heterogeneous electrolyte between the anode and the cathode current collector, comprising a first electrolyte solvent and a second electrolyte solvent, wherein the first electrolyte solvent is present disproportionately in the polymer gel layer at a molar or weight ratio of at least 2:1 relative to the second electrolyte solvent and the second electrolyte solvent is present disproportionately in a region between the polymer gel layer and the cathode current collector at a molar or weight ratio of at least 2:1 relative to the first electrolyte solvent.