Electrochemical energy devices are investigated as powers for electrified transportation. Li-ion batteries (LIBs) as the state-of-art energy storage device provide an unacceptable driving range with a long charging time. Supercapacitors can be charged in seconds but suffer from extremely low energy density. The driving-range issue calls on new efforts beyond the intercalation chemistry. One promising system is the lithium-sulfur (Li-S) battery. It has a theoretical energy density more than five times of LIBs. However, the Li-S batteries have been plagued by many tough challenges. A major hurdle is the dendrite-growth problem on a lithium metal anode because dendrites cause a battery thermal runaway. Previous approaches fell short of addressing the issue fundamentally. I will present a unique strategy to tackle this problem. For the sulfur electrode, it suffers low utilization and rapid capacity fading due to its poor conductivity and the polysulfide-dissolution problem. A suite of strategies will be described to address the challenges. In order to make supercapacitor relevant for transportation purposes, the energy density must be improved without comprising the durability and short charge time. A methodology that mechanistically combines the chemistries of supercapacitors and batteries will be described.
