Enhanced Kinetics Harvested in Heteroatom Dual-Doped Graphitic Hollow Architectures toward High Rate Printable Potassium-Ion Batteries

© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Carbonaceous materials have emerged as promising anode candidates for potassium-ion batteries (PIBs) due to overwhelming advantages including cost-effectiveness and wide availability of materials. However, further development in this realm is handicapped by the deficiency in their in-target and large-scale synthesis, as well as their low specific capacity and huge volume expansion. Herein the precise and scalable synthesis of N/S dual-doped graphitic hollow architectures (NSG) via direct plasma enhanced chemical vapor deposition is reported. Thus-fabricated NSG affording uniform nitrogen/sulfur co-doping, possesses ample potassiophilic surface moieties, effective electron/ion-transport pathways, and high structural stability, which bestow it with high rate capability (≈100 mAh g−1 at 20 A g−1) and a prolonged cycle life (a capacity retention rate of 90.2% at 5 A g−1 after 5000 cycles), important steps toward high-performance K-ion storage. The enhanced kinetics of the NSG anode are systematically probed by theoretical simulations combined with operando Raman spectroscopy, ex situ X-ray photoelectron spectroscopy, and galvanostatic intermittent titration technique measurements. In further contexts, printed NSG electrodes with tunable mass loading (1.84, 3.64, and 5.65 mg cm−2) are realized to showcase high areal capacities. This study demonstrates the construction of a printable carbon-based PIB anode, that holds great promise for next-generation grid-scale PIB applications

In situ construction of CoSe2@vertical-oriented graphene arrays as self-supporting electrodes for sodium-ion capacitors and electrocatalytic oxygen evolution

Transitional metal dichacogenides (TMDs) have stimulated an increasing research and technological attention due to their unique properties, holding great promise for emerging energy storage and conversion applications. However, tailorable and efficient synthesis of TMDs to garner the electrochemical and electrocatalytic performance of thus-derived electrodes has by far remained challenging. Herein we demonstrate a versatile synthetic strategy to in situ grow CoSe 2 @vertically-oriented graphene (VG) hierarchical architecture on carbon fiber cloth (CC) via combined steps of plasma-enhanced chemical vapor deposition and wet chemistry. Such self-supporting and flexible CoSe 2 @VG/CC arrays possess significant implications for pseudocapacitive Na storage and electrocatalytic O 2 evolution (OER). When evaluated as an anode material for sodium-ion hybrid capacitors, full cells comprising a CoSe 2 @VG/CC anode and AC cathode enable a favorable cyclic stability at 0.5 A g −1 for 1800 cycles in the potential range of 0.5-3.3 V, harvesting a high energy and power density of 116 Wh kg −1 and 7298 W kg −1 . In addition, CoSe 2 @VG/CC array also exhibits an excellent OER performance with a low overpotential of 418 mV and Tafel slope of 82 mV dec −1 on a basis of experimental exploration and theoretical simulation