Artificial SEI transplantation for insertion anodes
View Patent ↗An insertion anode for a Li-ion cell, protected with an SEI by pre-treatment in an SEI-formation cell, is stable for cell cycling even in the presence of substantial water in the cell electrolyte. A method for making the protected anode includes forming an SEI on a lithium-ion insertion electrode by performing multiple charge/discharge cycles on the electrode in a first cell having an SEI formation electrolyte to produce the protected anode. The SEI formation electrolyte includes an ionic liquid having at least one of twelve organic cations.
1. A method for preparing a lithium-ion cell having a protected insertion anode with a pre-formed solid electrolyte interphase (SEI), the method comprising:
forming an SEI on at least one lithium-ion insertion electrode by performing cyclic lithiation/delithiation on the lithium-ion insertion electrode in a cell having an SEI formation electrolyte to produce the protected insertion anode, the SEI formation electrolyte comprising:
a lithium salt selected from the group consisting of:
lithium bis(fluorosulfonyl)imide (LiFSI),
lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and
lithium dicyanamide (LiDCA); and
an ionic liquid comprising:
an organic cation selected from the group consisting of: 1-methyl-1-propylpyrrolidinium; N-methyl-N,N-diethyl-N-propylammonium; N,N-diethyl-N-methyl-N-(2-methoxyethyl)-ammonium; 1,1-methylpropylpiperidinium; N-methyl-N-(2-methoxyethyl)-pyrrolidinium; trimethylisopropylphosphonium; methyltriethylphosphonium; methyltributylphosphonium; N,N-dimethyl-N-(2-methoxyethyl)-N-ethyl-ammonium; 1-methyl-1-butylpyrrolidinium; N-methyl-N′-ethylimidazolium); N,N,N-trimethyl-N-propylammonium; and mixtures thereof; and
an anion selected from the group consisting of FSI, TFSI, and DCA; and
assembling a wet lithium-ion cell comprising:
the protected anode; and
a wet electrolyte in contact with the protected anode, the wet electrolyte comprising at least 10,000 ppm water.
2. The method as recited in claim 1 , wherein the at least one lithium-ion insertion electrode comprises at least one of an intercalation anode, a conversion anode, and an alloy anode.
3. The method as recited in claim 1 , wherein the at least one lithium-ion insertion electrode comprises lithium titanate.
4. The method as recited in claim 1 , wherein the lithium salt is present at a molar ratio, relative to ionic liquid of: at least 1:1.
5. The method as recited in claim 1 , wherein the lithium salt is present at its saturation point in the ionic liquid.
6. The method as recited in claim 1 , further comprising, prior to assembling the wet lithium-ion cell, washing the protected anode with a solvent in which the SEI formation electrolyte is soluble.
7. The method as recited in claim 1 , wherein the SEI formation electrolyte has a water content of less than 50 ppm.
8. The method as recited in claim 1 , wherein the wet electrolyte comprises water present at a concentration of at least 20,000 ppm.
9. The method as recited in claim 1 , wherein the cyclic lithiation/delithiation is performed at a lithiation voltage less than about 0.1 V.
10. The method as recited in claim 1 , wherein a surface of the protected insertion anode comprises at least 5% fluorine.
11. The method as recited in claim 1 , wherein a surface of the protected insertion anode comprises at least 0.5% sulfur.
12. The method as recited in claim 1 , wherein the cation comprises Pyr13.
13. The method as recited in claim 1 , wherein the cation comprises N1223.
14. The method as recited in claim 1 , wherein the cation comprises DEME.
15. The method as recited in claim 1 , wherein the cation comprises Pip13.
16. The method as recited in claim 1 , wherein the cation comprises P111 i 4.
17. The method as recited in claim 1 , wherein the cation comprises Pyr12 O 1.
18. The method as recited in claim 1 , wherein the cation comprises P1222.
19. The method as recited in claim 1 , wherein the cation comprises P1444.
20. A method for preparing a lithium-ion cell having a protected insertion anode with a pre-formed solid electrolyte interphase (SEI), the method comprising:
forming an SEI on at least one lithium-ion insertion electrode by performing cyclic lithiation/delithiation on the lithium-ion insertion electrode in a first cell having an SEI formation electrolyte to produce the protected insertion anode, the SEI formation electrolyte having a water concentration less than about 50 ppm, and comprising:
lithium bis(fluorosulfonyl)imide (LiFSI); and
an ionic liquid comprising:
an organic cation selected from the group consisting of: 1-methyl-1-propylpyrrolidinium; N-methyl-N,N-diethyl-N-propylammonium; N,N-diethyl-N-methyl-N-(2-methoxyethyl)-ammonium; 1,1-methylpropylpiperidinium; N-methyl-N-(2-methoxyethyl)-pyrrolidinium; trimethylisopropylphosphonium; methyltriethylphosphonium; methyltributylphosphonium; N,N-dimethyl-N-(2-methoxyethyl)-N-ethyl-ammonium; 1-methyl-1-butylpyrrolidinium; N-methyl-N′-ethylimidazolium); N,N,N-trimethyl-N-propylammonium; and mixtures thereof; and
bis(fluorosulfonyl)imide anion; and
assembling a wet Li-ion voltaic cell comprising:
the protected anode; and
a wet electrolyte in contact with the protected anode, the wet electrolyte comprising at least 10,000 ppm water.