Thin-walled porous carbon tile-packed paper for high-rate Zn-ion capacitor cathode

Long ion pathway inside large-sized carbon particle or stacked 2D assembly greatly limit the electrochemical performance of practical carbon cathode (> 10 mg cm(-2)) in Zn//C capacitors. Highly porous activated carbon and holy graphene can alleviate such ion-transport issue, but usually suffer from a far lower packing density and severe restacking, respectively. Herein, a kapok-derived quasi-2D thin-walled microporous carbon tile (CT) with optimized curvature and rich doping was developed and used as bricks. Assisted with single-walled carbon nanotubes (SWNTs), a porous yet relatively packed paper cathode was constructed. The unique doped thin wall (~700 nm) can effectively shorten the ion-penetration pathways from electrolyte deep into pore structure inside CTs, and thus enlarge ion-accessible surface areas. Combined with rational sub-micron interlayer spacing among proper-curved CTs and bridged-like SWNTs, the continuous ion/charge transport highways are fabricated. As a result, such self-standing carbon cathode delivers outstanding rate and gravimetric/areal performance (114 mAh g(-1)/1.37 mAh cm(-2)) without sacrificing volumetric capacity even at high mass loading (12 mg cm(-2)).

Automated summary

In this study, we developed a kapok-derived quasi-2D thin-walled microporous carbon tile (CT) and combined it with single-walled carbon nanotubes (SWNTs) to construct a porous paper cathode. The results showed that this carbon cathode exhibited outstanding performance even at high mass loading.