Flame-resistant quasi-solid hybrid electrolyte for safe lithium batteries and production method

A rechargeable lithium cell comprising a cathode having a cathode active material, an anode having an anode active material, a separator electronically separating said anode and said cathode, a non-flammable quasi-solid electrolyte comprising two electrolyte compositions:

• (a) A first electrolyte composition in physical contact with said cathode and said anode, wherein said first electrolyte composition contains a lithium salt dissolved in a mixture of a liquid solvent and a flame-retardant additive, having a lithium salt concentration C1;
• from 1.5 M to 14.0 M so that said electrolyte exhibits a vapor pressure less than 0.01 kPa when measured at 20° C., a vapor pressure less than 60% of the vapor pressure of said liquid solvent alone, a flash point at least 20 degrees Celsius higher than a flash point of said liquid solvent alone, a flash point higher than 150° C., or no flash point;
• and
• (b) A second electrolyte composition, comprising a polymer electrolyte in ionic contact with said first electrolyte composition and being disposed between the anode and the cathode, between the separator and the cathode and/or between the separator and the anode.