TY - JOUR A1 - Hwang, Jinyeon A1 - Zhang, Wuyong A1 - Youk, Sol A1 - Schutjajew, Konstantin A1 - Oschatz, Martin T1 - Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials JF - Energy technology : generation, conversion, storage, distribution N2 - The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites. KW - anodes KW - hybrid materials KW - nitrogen-doped carbon KW - porous carbon KW - lithium-ion capacitors Y1 - 2021 U6 - https://doi.org/10.1002/ente.202001054 SN - 2194-4296 VL - 9 IS - 3 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Yan, Runyu A1 - Josef, Elinor A1 - Huang, Haijian A1 - Leus, Karen A1 - Niederberger, Markus A1 - Hofmann, Jan P. A1 - Walczak, Ralf A1 - Antonietti, Markus A1 - Oschatz, Martin T1 - Understanding the charge storage mechanism to achieve high capacity and fast ion storage in sodium-ion capacitor anodes by using electrospun nitrogen-doped carbon fibers JF - Advanced functional materials N2 - Microporous nitrogen-rich carbon fibers (HAT-CNFs) are produced by electrospinning a mixture of hexaazatriphenylene-hexacarbonitrile (HAT-CN) and polyvinylpyrrolidone and subsequent thermal condensation. Bonding motives, electronic structure, content of nitrogen heteroatoms, porosity, and degree of carbon stacking can be controlled by the condensation temperature due to the use of the HAT-CN with predefined nitrogen binding motives. The HAT-CNFs show remarkable reversible capacities (395 mAh g(-1) at 0.1 A g(-1)) and rate capabilities (106 mAh g(-1) at 10 A g(-1)) as an anode material for sodium storage, resulting from the abundant heteroatoms, enhanced electrical conductivity, and rapid charge carrier transport in the nanoporous structure of the 1D fibers. HAT-CNFs also serve as a series of model compounds for the investigation of the contribution of sodium storage by intercalation and reversible binding on nitrogen sites at different rates. There is an increasing contribution of intercalation to the charge storage with increasing condensation temperature which becomes less active at high rates. A hybrid sodium-ion capacitor full cell combining HAT-CNF as the anode and salt-templated porous carbon as the cathode provides remarkable performance in the voltage range of 0.5-4.0 V (95 Wh kg(-1) at 0.19 kW kg(-1) and 18 Wh kg(-1) at 13 kW kg(-1)). KW - carbon fibers KW - nitrogen-doped carbon KW - sodium-ion capacitors KW - sodium storage mechanism Y1 - 2019 U6 - https://doi.org/10.1002/adfm.201902858 SN - 1616-301X SN - 1616-3028 VL - 29 IS - 26 PB - Wiley-VCH CY - Weinheim ER -