Electrolytes for lithium batteries
Aspects of the present disclosure are directed towards increases in cycle life and stability of electrochemical cells. Electrolytes and electrochemical cells, including those for use in rechargeable lithium batteries, are generally provided. In some embodiments, the electrolytes and electrochemical cells comprise asymmetric sulfonamides. The electrolytes and electrochemical cells also comprise carbonates, according to some embodiments.
1. An electrochemical cell, comprising:
a first electrode comprising lithium;
a first solvent comprising an asymmetric sulfonamide; and
a second solvent, wherein the second solvent comprises both a cyclic carbonate and a linear carbonate,
wherein the asymmetric sulfonamide has a formula (I):
wherein R 1 and R 2 can be the same or different and each is independently selected from unsubstituted, unbranched aliphatic chains; silyl substituents; or wherein R 1 and R 2 are connected to form an N-bound heterocycle;
wherein, if R 1 is selected from unsubstituted, unbranched aliphatic chains, R 1 comprises n carbon atoms, where n is an integer greater than or equal to 1 and less than or equal to 10;
wherein, if R 2 is selected from unsubstituted, unbranched aliphatic chains, R 2 comprises m carbon atoms, where m is an integer greater than or equal to 1 and less than or equal to 10;
wherein, if R 1 and R 2 are connected to form an N-bound heterocycle, the N-bound heterocycle comprises j carbon atoms, where j is an integer greater than or equal to 2 and less than or equal to 11;
wherein, if R 1 and/or R 2 is a silyl substituent, the silyl substituent has the form SiR 4 3 , where R 4 is an unsubstituted, unbranched aliphatic chain comprising k carbon atoms, where k is an integer greater than or equal to 1 and less than or equal to 10; and
wherein R 3 is an electron withdrawing species.
2. The electrochemical cell of claim 1 , wherein the electron withdrawing species is a halogen atom, substituted or unsubstituted, branched or unbranched haloaliphatic, —CN, —COOR 1 ,—C (═O)R 1 , —CON(R 1 ) 2 , —CONR 1 H, —NO 2 , —SO 3 R 1 , —SO(OR 1 ) 2 , —SO(OR 1 )H, —SOR 1 , —SO 2 R 1 , —PO(OR 1 ) 2 , —PO(OR 1 ) H, a protonated amine group (e.g., —NR 3 + and —NH 3 +), or a substituted aromatic group.
3. The electrochemical cell of claim 2 , wherein the substituted aromatic group comprises: a halogen atom, substituted or unsubstituted, branched or unbranched haloaliphatic, —CN, —COOR 1 , —C(═O)R 1 , —CON(R 1 ) 2 , —CONR 1 H, —NO 2 , —SO 3 R 1 , —SO(OR 1 ) 2 , —SO(OR 1 ) H, —SOR 1 , —SO 2 R 1 , —PO(OR 1 ) 2 , —PO(OR 1 ) H, and/or a protonated amine group (e.g.,—NR 3 + and —NH 3 +).
4. The electrochemical cell of claim 1 , wherein R 1 and R 2 are both unbranched aliphatic chains.
5. The electrochemical cell of claim 1 , wherein:
if R 1 is selected from unsubstituted, unbranched aliphatic chains, n is less than or equal to 4;
if R 2 is selected from unsubstituted, unbranched aliphatic chains, m is less than or equal to 4;
if R 1 and R 2 are connected to form an N-bound heterocycle, j is less than or equal to 7;
and/or
if R 1 and/or R 2 is a silyl substituent, k is less than or equal to 4.
6. The electrochemical cell of claim 1 , wherein R 1 is a silyl substituent.
7. The electrochemical cell of claim 1 , wherein R 2 is a silyl substituent.
8. The electrochemical cell of claim 1 , wherein R 1 and R 2 are connected to form an N-bound heterocycle.
9. The electrochemical cell of claim 1 , wherein the linear carbonate has the chemical structure (II)
wherein R 5 and R 6 can be the same or different, and are both selected from unsubstituted, branched or unbranched aliphatic; substituted or unsubstituted, branched or unbranched haloaliphatic; or substituted or unsubstituted, branched or unbranched haloheteroaliphatic chains comprising between 1 and 10 carbon atoms.
10. The electrochemical cell of claim 1 , wherein the cyclic carbonate has the chemical structure (III);
wherein R 7 connects two oxygen atoms to form a heterocycle, and is selected from unsubstituted, unbranched aliphatic; substituted or unsubstituted, unbranched haloaliphatic; or substituted or unsubstituted, unbranched haloheteroaliphatic chains comprising between 1 and 10 carbon atoms.
11. The electrochemical cell of claim 1 , wherein the molar ratio between the linear carbonate and the cyclic carbonate is between 0:1 and 10:1.
12. The electrochemical cell of claim 1 , wherein the molar ratio between the linear carbonate and the cyclic carbonate is between 1:6 and 1:3.
13. The electrochemical cell of claim 1 , wherein the linear carbonate is dimethyl carbonate or ethylmethyl carbonate.
14. The electrochemical cell of claim 1 , wherein the cyclic carbonate is fluoroethylene carbonate.
15. The electrochemical cell of claim 1 , wherein the electrochemical cell further comprises a salt.
16. The electrochemical cell of claim 1 , further comprising a second electrode.
17. The electrochemical cell of claim 16 , wherein the second electrode comprises lithium.
18. The electrochemical cell of claim 16 , wherein the second electrode comprises lithium metal or lithium metal alloy.
19. The electrochemical cell of claim 1 , wherein the first electrode is a lithium-intercalation cathode.
20. An electrochemical cell, comprising:
an electrode comprising lithium; and
an asymmetric sulfonamide;
wherein the asymmetric sulfonamide has a formula (I);
wherein R 1 and R 2 can be the same or different and each is selected from unsubstituted, unbranched aliphatic chains; silyl substituents; or wherein R 1 and R 2 are connected to form an N-bound heterocycle;
wherein, if R 1 is selected from unsubstituted, unbranched aliphatic chains, R 1 comprises n carbon atoms, where n is an integer greater than or equal to 1 and less than or equal to 10, and R 2 is a silyl substituent;
wherein, if R 2 is selected from unsubstituted, unbranched aliphatic chains, R 2 comprises m carbon atoms, where m is an integer greater than or equal to 1 and less than or equal to 10, and R 1 is a silyl substituent;
wherein, if R 1 and R 2 are connected to form an N-bound heterocycle, the N-bound heterocycle, comprises j carbon atoms, where j is an integer greater than or equal to 2 and less than or equal to 11;
wherein, if R 1 and/or R 2 is a silyl substituent, the silyl substituent has the form SiR 4 3 , where R 4 is an unsubstituted, unbranched aliphatic chain comprising k carbon atoms, where k is an integer greater than or equal to 1 and less than or equal to 10; and
wherein R 3 is an electron withdrawing species.