Defect-Selectivity and "Order in Disorder" Engineering in Carbon for Durable and Fast Potassium Storage.

Defect-rich carbon materials possess high gravimetric potassium storage capability due to the abundance of active sites, but their cyclic stability is limited because of the low reversibility of undesirable defects and the deteriorative conductivity. Herein, we report an in-situ defect-selectivity and order in disorder synergetic engineering in carbon materials via a self-template strategy to boost the K+ storage capacity, rate capability and cyclic stability simultaneously. The defect-sites are selectively tuned to realize abundant reversible carbon-vacancies as well as the sacrifice of poor-reversible heteroatom-defects through the persistent gas release during pyrolysis. Meanwhile, the nanobubbles generated during pyrolysis serve as the self-templates to induce the surface atom rearrangement, thus in-situ embedding nanographitic networks in defective domains without serious phase separation, which greatly enhance the intrinsic conductivity. The synergetic "order in disorder" structure ensures high concentration of reversible carbon-vacancies and fast charge transfer kinetics simultaneously, leading to high reversible capacity (425 mAh g-1 at 0.05 A g-1 ), high-rate (237.4 mAh g-1 at 1 A g-1 ) and superior cyclic stability (90.4% capacity retention from cycle 10 to 400 at 0.1 A g-1 ). This work provides a rational and facile strategy to realize the tradeoff between defect sites and intrinsic conductivity, and gives deep insights into the mechanism of reversible potassium storage. This article is protected by copyright. All rights reserved.