Method of producing non-flammable quasi-solid electrolyte and a quasi-solid electrolyte/separator layer for use in a lithium battery

A method of producing a separator/quasi-solid electrolyte layer for use in a lithium battery, said method comprising:

• (a) providing an ion-permeable or porous thin-film separator, wherein said separator has a thickness less than 500 μm;
• (b) dissolving a lithium salt in a first liquid solvent to obtain a flowable liquid mixture having a first concentration of lithium salt less than 3.0 M (mole/L), but greater than 0.001M, wherein said first liquid solvent further comprises an additive, wherein said additive is different in composition than said first liquid solvent and is selected from Tris(trimethylsilyl) phosphite (TTSPi), Triallyl phosphate (TAP), Ethylene sulfate (DTD), 1,3-propane sultone (PS), Propene sultone (PES), Alkylsiloxane (Si—O), Alkyylsilane (Si—C), liquid oligomeric silaxane (—Si—O—Si—), or a combination thereof, wherein said first liquid solvent further comprises a second liquid solvent mixed with said first liquid solvent to dissolve said lithium salt and the method further comprises partially or totally removing said second solvent after the lithium salt is dissolved, wherein said second liquid solvent is selected from acetone, an alcohol, or a combination thereof;
• and
• (c) coating or impregnating said thin-film separator with said flowable liquid mixture to obtain a separator/electrolyte layer and removing a portion of said first liquid solvent to obtain a separator/quasi-solid electrolyte having a final lithium salt concentration higher than said first concentration.