An Extremely High Surface Area Mesoporous-Microporous-Networked Pillared Carbon for High Stability Li-S and Intermediate Temperature Na-S Batteries

Abstract

A high surface area porous carbon synthesized using a sacrificial-template assisted synthesis protocol, is demonstrated here as a host for the confinement of sulfur for use in Li−S and intermediate temperature (25-70 °C) Na−S rechargeable batteries. The hierarchical porous pillared carbon host, comprising of an intricate network of mesopores and micropores provide a landscape of sites with varying strength of interaction with sulfur. Thus, the amount of sulfur (and associated polysulfides) inside the carbon host is predetermined by the host structural characteristics rather than by the loading protocol. The mesoporous-microporous carbon led to sulfur content in excess of 70%. While the bulk of S (and polysulfides) are stored inside the mesopores of the carbon host, the micropore apart from sulfur storage strongly contributes towards the modulation of sulfur flux during charge-discharge cycling. The S−C cathode exhibited remarkable cycling and rate capability with Li and also against Na at intermediate temperature (25-70 °C). This result is a paradigm shift from the conventional Na−S electrochemistry which is known to efficiently work only at elevated temperatures, in the temperature range starting from excess of 100 °C to 300 °C.