Electrolyte additives for electrochemical devices
A system and method for stabilizing electrodes against dissolution and/or hydrolysis including use of cosolvents in liquid electrolyte batteries for three purposes: the extension of the calendar and cycle life time of electrodes that are partially soluble in liquid electrolytes, the purpose of limiting the rate of electrolysis of water into hydrogen and oxygen as a side reaction during battery operation, and for the purpose of cost reduction.
1. A rechargeable electrochemical device, comprising:
a first electrode;
a second electrode;
an electrolyte coupled with said electrodes; and
a first additive in communication with said electrolyte;
wherein a first particular one electrode of said electrodes includes a first variable potential material having a first electrochemical potential V0 with said first electrochemical potential V0 having a potential range of V1 at full charge to V2 at full discharge;
wherein a second particular one electrode different from said first particular one electrode includes a second material having a second electrochemical potential V3; and
wherein said first additive is configured to participate in a first electrochemical reaction at an electrochemical potential V4 with said first particular one electrode degrading a charging efficiency of said first particular one electrode; and
wherein said reaction electrochemical potential V4 has a value between said first electrochemical potential V0 and said second electrochemical potential V3.
2. The rechargeable electrochemical device of claim 1 wherein a charging of said electrodes produces a relative state-of-charge imbalance between said electrodes, wherein said electrochemical reaction includes a duration, and wherein said duration is preconfigured to reduce said relative state-of-charge imbalance between said electrodes.
3. The rechargeable electrochemical device of claim 1 wherein said first particular one electrode includes a first transition metal cyanide coordination compound (TMCCC).
4. The rechargeable electrochemical device of claim 1 further comprising a second additive in communication with said electrolyte wherein a second particular one electrode of said electrodes, different from said first particular one electrode of said electrodes, includes a second variable potential material; and wherein said second additive participates in a second predetermined side-reaction with a second single one of said electrodes.
5. The rechargeable electrochemical device of claim 4 wherein said second particular one electrode includes a second transition metal cyanide coordination compound (TMCCC).
6. The rechargeable electrochemical device of claim 3 wherein said TMCCC material includes a composition having the general chemical formula A x M y [R(CN) 6-j L j ] z .nH 2 O, wherein:
A includes one or more cations;
M includes one or more metal cations;
R includes one or more transition metal cations; and
L is a ligand substituted in the place of a CN − ligand; where
0≤ x≤ 2;
0< y≤ 4;
0< z≤ 1;
0≤ j< 6; and
0≤ n≤ 5.
7. The rechargeable electrochemical device of claim 1 wherein a concentration of said additive is included within a range of 10 to 10,000 parts per million.
8. The rechargeable electrochemical device of claim 1 wherein said additive includes one or more organic molecules.
9. The rechargeable electrochemical device of claim 8 wherein said one or more organic molecules are configured to participate in a reversible electrochemical redox reaction at one or more of said electrodes during an application of charging energy to said electrodes.
10. The rechargeable electrochemical device of claim 8 wherein said one or more organic molecules are configured to participate in an irreversible electrochemical redox reaction at one or more of said electrodes during an application of charging energy to said electrodes.
11. The rechargeable electrochemical device of claim 10 wherein said irreversible electrochemical redox reaction results in a polymerization of said one or more organic molecules.
12. The rechargeable electrochemical device of claim 1 wherein said additive includes a transition metal salt.
13. The rechargeable electrochemical device of claim 12 wherein said salt is configured to participate in a reversible electrochemical redox reaction at one or more of said electrodes during an application of charging energy to said electrodes.
14. The rechargeable electrochemical device of claim 12 wherein said salt is configured to participate in an irreversible reaction at one or more of said electrodes during an application of charging energy to said electrodes.
15. The rechargeable electrochemical device of claim 12 wherein said salt includes a transition metal cation.
16. The rechargeable electrochemical device of claim 12 wherein said salt includes a transition metal polyanion.
17. The rechargeable electrochemical device of claim 1 wherein said additive includes an organometallic molecule.
18. The rechargeable electrochemical device of claim 17 wherein said first electrochemical reaction is reversible and wherein said organometallic molecule is configured to participate in said first electrochemical reaction.
19. The rechargeable electrochemical device of claim 17 wherein said organometallic molecule includes a metallocene.
20. A method for reducing a relative state-of-charge imbalance of a set of electrodes of a rechargeable electrochemical device during a charging process, the set of electrodes coupled to an electrolyte including a first additive and wherein a first one electrode of the set of electrodes includes a first variable potential material, comprising:
a) performing the charging process which charges the set of electrodes at different relative rates producing a relative state-of-charge imbalance for the set of electrodes; and
b) decreasing said relative state-of-charge imbalance responsive to an interference with a charging efficiency of at least one electrode of the set of electrodes.
21. The rechargeable electrochemical device of claim 1 wherein said first additive is initially in an oxidized state, wherein said first electrochemical reaction includes a reaction in which said additive is reduced, and wherein said reaction electrochemical potential V4 is greater than or equal to said first electrochemical potential V0.
22. The rechargeable electrochemical device of claim 21 wherein a charging of said electrodes produces a relative state-of-charge imbalance between said electrodes, wherein said first electrochemical potential V0 is initially greater than said reaction electrochemical potential V4, wherein said first electrochemical potential V0 is responsive to said charging to decrease towards V1, wherein said reaction in which said additive is reduced is configured to begin decreasing said relative state-of-charge imbalance when said first electrochemical potential V0, responsive to said charging, is less than said reaction electrochemical potential V4.
23. The rechargeable electrochemical device of claim 1 wherein said first additive is initially in a reduced state, wherein said first electrochemical reaction includes a reaction in which said additive is oxidized, and wherein said reaction electrochemical potential V4 is less than or equal to said first electrochemical potential V0.
24. The rechargeable electrochemical device of claim 23 wherein a charging of said electrodes produces a relative state-of-charge imbalance between said electrodes, wherein said first electrochemical potential V0 is initially lesser than said reaction electrochemical potential V4, wherein said first electrochemical potential V0 is responsive to said charging to increase towards V1, wherein said reaction in which said additive is oxidized is configured to begin decreasing said relative state-of-charge imbalance when said first electrochemical potential V0, responsive to said charging, is greater than said reaction electrochemical potential V4.
25. The method of claim 20 wherein the first variable potential material includes a first electrochemical potential V0 with said first electrochemical potential V0 having a potential range of V1 at full charge to V2 at full discharge, wherein the set of electrodes includes a second electrode different from the first electrode, said second electrode including a second material having a second electrochemical potential V3, wherein the first additive is configured to participate in a first electrochemical reaction at an electrochemical potential V4 with the first electrode producing said interference, and wherein said electrochemical potential V4 has a value between said first electrochemical potential V0 and said second electrochemical potential V3.
26. The method of claim 25 wherein the first additive is initially in an oxidized state, wherein said first electrochemical reaction includes a reaction in which said additive is reduced, and wherein said reaction electrochemical potential V4 is greater than or equal to said first electrochemical potential V0.
27. The method of claim 26 wherein a charging of said electrodes produces said relative state-of-charge imbalance between said electrodes, wherein said first electrochemical potential V0 is initially greater than said reaction electrochemical potential V4, wherein said first electrochemical potential V0 is responsive to said charging to decrease towards V1, wherein said reaction in which said additive is reduced is configured to begin decreasing said relative state-of-charge imbalance when said first electrochemical potential V0, responsive to said charging, is less than said reaction electrochemical potential V4.
28. The method of claim 25 wherein the first additive is initially in a reduced state, wherein said first electrochemical reaction includes a reaction in which said additive is oxidized, and wherein said reaction electrochemical potential V4 is less than or equal to said first electrochemical potential V0.
29. The method of claim 28 wherein a charging of said electrodes produces said relative state-of-charge imbalance between said electrodes, wherein said first electrochemical potential V0 is initially lesser than said reaction electrochemical potential V4, wherein said first electrochemical potential V0 is responsive to said charging to increase towards V1, wherein said reaction in which said additive is oxidized is configured to begin decreasing said relative state-of-charge imbalance when said first electrochemical potential V0, responsive to said charging, is greater than said reaction electrochemical potential V4.