Electrolytes and separators for lithium metal batteries

An electrochemical cell that cycles lithium ions comprising:

• a positive electrode having a first plurality of pores;
• a negative electrode having a second plurality of pores comprising a lithium metal;
• a separator disposed between the positive electrode and the negative electrode, the separator having a third plurality of pores and one or more coatings at least partially coating pore walls of the third plurality of pores, at least one of the one or more coatings comprising alucone;
• and
• a liquid electrolyte system that at least partially fills the first plurality of pores, the second plurality of pores, and the third plurality of pores and also voids between the positive electrode, the negative electrode, and the separator, wherein the liquid electrolyte system comprises:
• two or more lithium salts, wherein the two or more lithium salts comprises greater than or equal to about 0.1M to less than or equal to about 0.9M of a first lithium salt and greater than or equal to about 0.1M to less than or equal to about 0.9M of a second lithium salt, wherein the first lithium salt is lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LIFSI) and the second lithium salt is lithium perchlorate (LiClO4);
• and
• two or more solvents, wherein the two or more solvents comprises a first solvent and a second solvent, wherein the first solvent is fluoroethylene carbonate (FEC) and the second solvent is selected from the group consisting of:
• dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethylcarbonate (EMC), 1,2-dimethoxyethane (DME), and combinations thereof.

An electrochemical cell that cycles lithium ions comprising:

• a negative electrode having a first plurality of pores and comprising a lithium metal;
• a surface-modified separator having a second plurality pores and comprising one or more coatings at least partially coating pore walls of the second plurality of pores, wherein each of the one or more coatings comprises alucone;
• a solid electrolyte interface (SEI) layer disposed between the negative electrode and the surface-modified separator;
• and
• a liquid electrolyte system that at least partially fills the first plurality of pores and the second plurality of pores and also voids between the negative electrode, the separator, and the solid electrolyte interface (SEI) layer, wherein the liquid electrolyte system comprises:
• two or more lithium salts, wherein the two or more lithium salts comprises greater than or equal to about 0.1M to less than or equal to about 0.9M of a first lithium salt and greater than or equal to about 0.1M to less than or equal to about 0.9M of a second lithium salt, wherein the first lithium salt is lithium bis(fluorosulfonyl)imide (LiN(FSO2)2) (LIFSI) and the second lithium salt is lithium perchlorate (LiClO4);
• and
• two or more solvents, wherein the two or more solvents comprises a first solvent and a second solvent, wherein the first solvent is fluoroethylene carbonate (FEC) and the second solvent is selected from the group consisting of:
• dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethylcarbonate (EMC), 1,2-dimethoxyethane (DME), and combinations thereof.