Methods of charging lithium-sulfur batteries
First Claim
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1. A method of increasing the cycle life of a lithium electrochemical cell, wherein said method comprises the steps of:
- (a) discharging said cell at an overall rate of less than 0.5 mA/cm2;
(b) charging said cell at an initial low charge rate of less than 0.2 mA/cm2 to a cell voltage in the range of 2.1 to 2.3 V; and
(c) subsequently charging said cell at a high charge rate of greater than 0.2 mA/cm2 to a cell voltage of at least 2.4 V;
wherein said cell comprises;
(i) an anode comprising lithium;
(ii) a cathode comprising an electroactive sulfur-containing material; and
(iii) a liquid electrolyte interposed between said anode and said cathode.
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Abstract
Provided is a method for increasing the cycle life of discharged lithium electrochemical cells, wherein the cell comprises (i) an anode comprising lithium; (ii) a cathode comprising an electroactive sulfur-containing material; and (iii) a liquid electrolyte interposed between the anode and cathode; wherein the method comprises the steps of: (a) charging the cell at an initial low rate of less than 0.2 mA/cm2 to a cell voltage in the range of 2.1 to 2.3 V followed by (b) a subsequent high rate of greater than 0.2 mA/cm2 to a cell voltage of at least 2.4 V.
72 Citations
24 Claims
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1. A method of increasing the cycle life of a lithium electrochemical cell, wherein said method comprises the steps of:
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(a) discharging said cell at an overall rate of less than 0.5 mA/cm2;
(b) charging said cell at an initial low charge rate of less than 0.2 mA/cm2 to a cell voltage in the range of 2.1 to 2.3 V; and
(c) subsequently charging said cell at a high charge rate of greater than 0.2 mA/cm2 to a cell voltage of at least 2.4 V;
wherein said cell comprises;
(i) an anode comprising lithium;
(ii) a cathode comprising an electroactive sulfur-containing material; and
(iii) a liquid electrolyte interposed between said anode and said cathode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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15. The method of claim 1, wherein said electroactive sulfur-containing material, in its oxidized state, comprises one or more of the polysulfur moieties:
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wherein m, the same or different at each occurrence, is an integer and is greater than 2, and y, the same or different at each occurrence, is an integer and is equal to or greater than 1.
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16. The method of claim 1, wherein said electroactive sulfur-containing material, in its oxidized state, comprises one or more of the moieties:
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wherein m is the same or different at each occurrence and is greater than 2.
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17. The method of claim 1, wherein said electroactive sulfur-containing material is a polymer comprising polymeric segments of the formula:
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wherein; Q denotes a carbocyclic repeat unit comprising a carbocycle having from 3 to 12 ring carbon atoms;
S denotes a sulfur atom;
m is the number of sulfur atoms in a given polysulfide linkage, is an integer from 3 to 10, and is the same or different at each occurrence;
n denotes the number of crosslinking polysulfide linkages, is an integer from 1 to 20, and is the same or different at each occurrence; and
p is an integer greater than 1.
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18. The method of claim 1, wherein said electroactive sulfur-containing material comprises greater than 50% by weight of sulfur.
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19. The method of claim 1, wherein said electroactive sulfur-containing material comprises greater than 75% by weight of sulfur.
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20. The method of claim 1, wherein said electroactive sulfur-containing material comprises greater than 90% by weight of sulfur.
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21. The method of claim 1, wherein said anode comprises lithium metal.
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22. The method of claim 1, wherein said liquid electrolyte comprises:
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(i) one or more lithium salts; and
(ii) one or more non-aqueous solvents.
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23. The method of claim 22, wherein said one or more lithium salts are selected from the group consisting of LiBr, LiI, LiSCN, LiBF4, LiPF6, LiAsF6, LiSO3CF3, LiN(SO2CF3)2, LiC(SO2CF3)3, (LiSx)zR, and Li2Sx, where x is an integer from 1 to 20, z is an integer from 1 to 3, and R is an organic group.
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24. The method of claim 22, wherein said one or more non-aqueous solvents are selected from the group consisting of ethers, cyclic ethers, polyethers, esters, sulfones, and sulfolanes.
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Specification