High-rate lithium-sulfur batteries enabled by hierarchical porous carbons synthesized via ice templation

Abstract

We report the performance of a series of hierarchical porous carbons (HPCs) with extremely high surface areas of up to 2340 m² g^-1 with total pore volume of up to 3.8 cm³ g^-1 as supports for sulfur for Li-S batteries. The hierarchical structure of the carbon originating from interconnected large mesopores (10-50 nm), small mesopores (2-10 nm) and micropores (<2 nm) makes the total available surface area highly accessible, resulting in excellent electrode kinetics. At high C-rates of 2 C and 5 C, large specific capacities of 647 mA h g^-1 and 503 mA h g^-1, respectively, were obtained after 200 cycles. In addition, we also systematically show that the cyclic stability is independent of the size of the pores sulfur is initially confined in, when LiNO<inf>3</inf> is used as the electrolyte additive, indicating that capacity fade due to polysulfide shuttle is effectively eliminated and that it is not related to pore size anymore.