THIS PROJECT AIMS TO DEVELOP HIGH-PERFORMANCE LITHIUM BATTERIES FOR EXTREME LOW-TEMPERATURE OPERATION. UNLIKE CONVENTIONAL CELLS THAT USE LIQUID ELECTROLYTES WHICH SUFFER FROM LARGELY REDUCED IONIC CONDUCTIVITY (<-30 OC) AND INCREASED SURFACE RESISTANCE OUR PROPOSED CELLS WILL ADOPT HYDROFLUOROCARBON GAS ELECTROLYTES THAT ARE LIQUEFIED AT AMBIENT PRESSURE. THE SPECIFIC OBJECTIVES OF THE PROPOSED WORK INCLUDE: (1) TO DESIGN AND SYNTHESIZE ELECTROCHEMICALLY STABLE POROUS HOSTS (ELECTROLYTE AND ELECTRODES) FOR HYDROFLUOROCARBON CONDENSATION; (2) TO CONDENSE AND INFILTRATE GAS MOLECULES INTO THE POROUS HOSTS AT AMBIENT PRESSURE TO PRODUCE HYBRID ELECTROLYTES AND TEST ELECTROCHEMICAL PROPERTIES; (3) TO MAKE LITHIUM CELLS USING POROUS ELECTROLYTE AND ELECTRODES AND TEST THEIR PERFORMANCE. OUR APPROACH IS BASED ON CAPILLARY CONDENSATION OF HYDROFLUOROCARBON GAS MOLECULES IN NANOPOROUS STRUCTURES AT AMBIENT PRESSURE. IT HAS BEEN RECENTLY DEMONSTRATED THAT LIQUEFIED HYDROFLUOROCARBON GAS MOLECULES (E.G. FLUOROMETHANE) HAVE LARGE ELECTROCHEMICAL STABILITY WINDOW AND REASONABLY HIGH IONIC CONDUCTIVITY AND CAN FORM IONIC CONDUCTIVE ELECTROLYTE/ELECTRODE INTERFACE AT EXTREME LOW TEMPERATURE (-78 OC) ENABLING HIGH PERFORMANCE LITHIUM CELLS. HOWEVER LIQUEFICATION OF SUCH GAS MOLECULES NEEDS TO OVERCOME LARGE VAPOR PRESSURE (0.79-3.41 MPA) ABOUT 10 TIMES OF AMBIENT PRESSURE. THEREFORE THESE HYDROFLUOROCARBON SOLVENTS NEED SPECIAL HANDLING TO FABRICATE CELLS AND PREVENT LEAKAGE WHICH PLACES POTENTIAL CHALLENGE IN REAL APPLICATIONS. TO LIQUEFY HYDROFLUOROCARBON MOLECULES UNDER AMBIENT PRESSURE WILL ENABLE FABRICATION OF LITHIUM CELLS USING GASEOUS SOLVENT LIKE THE WAY FOR CONVENTIONAL LIQUID CELLS. THE KEY IS TO CONDENSE GAS MOLECULES AT SIGNIFICANTLY REDUCED VAPOR PRESSURE. THE KELVIN EQUATION SUGGESTS THAT IN A POROUS MEDIUM CAPILLARY CONDENSATION WILL ALWAYS OCCUR. THE SMALLER THE PORE DIAMETER THE LOWER THE EQUILIBRIUM VAPOR PRESSURE NEEDED TO CONDENSE GAS MOLECULES. BOTH SIMULATION AND EXPERIMENTAL RESULTS SHOW THAT THE OPERATING PRESSURE TO CONDENSE NITROGEN IN POROUS CARBON REDUCES BY>10 TIMES AS PORE SIZE DECREASES FROM 7 TO 1 NM. SIMILAR TREND HAS ALSO BEEN OBSERVED FOR METHANE. WHILE CAPILLARY CONDENSATION OF HYDROFLUOROCARBON HAS NOT BEEN SYSTEMATICALLY STUDIED YET BY APPLYING SIMILAR PRINCIPLE WE EXPECT THAT THE OPERATING PRESSURE REQUIRED TO CONDENSE HYDROFLUOROCARBON WILL BE REDUCED TO 0.08-0.34 MPA APPROACHING AMBIENT PRESSURE. THE KEY IS TO CREATE POROUS STRUCTURES THAT CAN HOST THESE MOLECULES AND MAINTAIN ELECTROCHEMICAL AND MECHANICAL STABILITY IN CELLS. THE MOST PROMISING POROUS STRUCTURES NEED TO HAVE SUB-10 NM PORES TO ALLOW A SIGNIFICANTLY REDUCED OPERATING VAPOR PRESSURE COMPARED WITH NORMAL CONDITIONS. THE FOCUS OF SUCH MATERIALS INCLUDES MESOPOROUS SILICA ZEOLITES AND METAL-ORGANIC FRAMEWORKS. BESIDES HAVING SMALL PORES (0.5~10 NM) THESE MATERIALS HAVE PREVIOUSLY BEEN EITHER USED AS ELECTROLYTE ADDITIVE OR AS THE HOST FOR LIQUID ELECTROLYTES CONFIRMING THEIR COMPATIBILITY WITH LITHIUM CHEMISTRY. NANOPOROUS ELECTRODES (E.G. MNO2 LICOO2 SNO2) CAN BE ALSO DEVELOPED IN THE PI'S LAB USING ESTABLISHED METHODS. THE PI WILL LEVERAGE HIS EXPERIENCE IN POROUS MATERIALS TO MAKE A BROAD RANGE OF HOST MATERIALS TO FOR TESTING HYDROFLUOROCARBON CONDENSATION AT AMBIENT PRESSURE. THE LIQUEFIED ELECTROLYTE (HYDROFLUOROCARBON TRAPPED IN HOSTS) AND POROUS ELECTRODES WILL BE USED FOR LITHIUM CELL FABRICATION AND ELECTROCHEMICAL CHARACTERIZATION. THE SUCCESS OF THIS PROJECT WILL GENERATE A NEW CLASS OF LITHIUM BATTERIES WITH HIGH PERFORMANCE AT EXTREME LOW TEMPERATURE. THE USE OF MECHANICALLY STABLE POROUS HOSTS AS THE GAS ELECTROLYTE MATRIXES MAY RESTRICT THE DENDRITE GROWTH IN ANODE A MAJOR PROBLEM FOR LITHIUM BATTERIES AT LOW TEMPERATURES. THESE FEATURES TOGETHER WILL MAKE OUR CELLS PROMISING FOR USE IN EXTREME COLD ENVIRONMENTS FOR EXAMPLE IN AEROSPACE APPLICATIONS.