Currently a Principal Member Technical Staff, he has been at the Jet Propulsion Laboratory for the last thirty years developing advanced electrochemical energy storage technologies, both primary and rechargeable batteries for space applications. His research areas include advanced lithium and lithium-ion batteries with novel organic, polymer and solid state electrolytes and with high specific energy cathode and and anode materials, lithium-sulfur batteries, aqueous batteries such as nickel-hydrogen, nickel-metal hydride and metal hydride-air batteries, high temperature sodium rechargeable batteries, advanced primary lithium batteries such as Li-SO2, Li-SOCl2 Li-CFx and hydrogen storage materials. Over the years, he has led or supported battery efforts on several flight missions including Mars Exploration Rovers, Mars Science laboratory (MSL), Mars Surveyor Program Lander, Outer planetary missions (Europa Clipper and Lander), Extra-Vehicular Activities (EVA), Kepler, Aquarius, Stardust, Genesis, CloudSat etc.