Novolac-derived carbons are very attractive due to the high carbon yield after synthesis, very low precursor material costs, and abundant availability. Using a template-free process, we synthesized sub-micrometer sized beads from a self-emulsifying novolac-ethanol-water system, which were pyrolyzed and activated with CO2. The specific surface area of the microporous novolac-derived carbons can be tuned by activation from 771-2237 m2/g, with a total pore volume of 0.28-1.71 m2/g. The spherical shape of the particles is thereby conserved. We investigated the performance of these novolac-derived carbon beads as advanced electrodes for electrochemical energy storage. Due to the small size of the primer particles, the performance at high charge / discharge rates in a supercapacitor in common electrolytes is superior compared to other commercial activated carbon materials (novolac-derived carbon: 75 F/g compared to YP-80F: 20 F/g; measured in tetraethylammonium tetrafluoroborate in propylene carbonate at 20 mA/g). The large pore volume of the carbon beads also yields a very attractive energy storage capacity of 33 Wh/kg in high concentrated aqueous potassium iodide redox electrolyte. The small size of the beads benefits rapid charge storage because of short diffusional pathways. Finally, we analyzed the performance of our carbon beads as host for sulfur in a lithium-sulfur battery. We infiltrated the nanoporous carbon materials via melt-infusion of sulfur and in situ formation from sodium thiosulfate aqueous solution. The best performance was obtained by melt-infusion of the activated samples (~880 mAh/gsulfur at low charge rate; 5th cycle) with a high performance stability (&gt;600 mAh/gsulfur after 100 cycles).

Sub-micrometer Novolac-derived carbon beads as electrodes for supercapacitors, redox electrolyte hybrids, and Li-S batteries

254th National Meeting (2017)

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