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ZnO hard templating for synthesis of hierarchical porous carbons with tailored porosity and high performance in lithium-sulfur battery

: Strubel, Patrick; Thieme, Sören; Biemelt, Tim; Helmer, Alexandra; Oschatz, Martin; Brückner, Jan; Althues, Holger; Kaskel, Stefan


Advanced Functional Materials 25 (2015), Nr.2, S.287-297
ISSN: 1616-301X
ISSN: 1616-3028
Fraunhofer IWS ()
porous carbon; pore tailoring; nanocasting; energy storage; lithium sulfur battery

Hierarchical porous carbon (HPC, DUT-106) with tailored pore structure is synthesized using a versatile approach based on ZnO nanoparticles avoiding limitations present in conventional silica hard templating approaches. The benefit of the process presented here is the removal of all pore building components by pyrolysis of the ZnO/carbon composite without any need for either toxic/reactive gases or purification of the as-prepared hierarchical porous carbon. The carbothermal reduction process is accompanied by an advantageous growing of distinctive micropores within the thin carbon walls. The resulting materials show not only high internal porosity (total pore volume up to 3.9 cm3 g−1) but also a large number of electrochemical reaction sites due to their remarkably high specific surface area (up to 3060 m2 g−1), which renders them particularly suitable for the application as sulfur host material. Applied in the lithium-sulfur battery, the HPC/sulfur composite exhibits a capacity of >1200 mAh g−1-sulfur (>750 mAh g−1 electrode) at a high sulfur loading of ≥ 3 mg cm−2 as well as outstanding rate capability. In fact, this impressive performance is achieved even using a low amount of electrolyte (6.8 μl mg−1 sulfur) allowing for further weight reduction and maintenance of high energy density on cell level.