Zinc-salt templating of hierarchical porous carbons for low electrolyte high energy lithium-sulfur batteries (LE-LiS)
Hierarchical porous carbons with small mesopores and distinctive microporosity within the carbon walls are prepared using an efficient zinc-salt based templating approach. The pyrolysis accompanied by carbothermal reduction enables in situ template removal without toxic/reactive gases as byproducts and no further purification steps are required. Since the hierarchical porous carbon offers a specific surface area exceeding 2600 m2 g−1 as well as a high internal pore volume of 2.46 cm3 g−1 the novel material is well suited as sulfur host material to be implemented in cathodes for lithium-sulfur batteries. This leads to an initial discharge capacity of 1225 mAh g−1sulfur and, moreover, a stable capacity of over 950 mAh g−1sulfur for 100 cycles. Of outstanding importance is the fact, that the synergistic advantage of the hierarchical pore network ensures remarkable sulfur utilizations as well as cycle stabilities at low electrolyte amounts down to 4 ml mg−1sulfur (coin cell). Low electrolyte LiS cell concepts (LE-LiS) are essential for the development of high energy density on cell level.