Approaching Superior Potassium Storage of Carbonaceous Anode Through a Combined Strategy of Carbon Hybridization and Sulfur Doping

Carbonaceous materials are promising anode candidates for potassium-ion batteries(PIBs)given its high conductivity,stable property,and abundant resource,while its practical implementation is still hampered by its limited capacity and inferior rate behavior.Herein,we report a superior carbonaceous anode through a combined strategy of carbon hybridization and heteroatom doping.In this composite,hollow carbon spindles(HCS)were anchored on the surface of graphene(G)followed with sulfur doping treatment,aiming to integrate the high conductivity of graphene,the good structure stability of HCS,and the S doping-induced ample active sites.As a PIB anode,the S-G@HCS composite can display high capacity(301 mAh g^(-1)at 0.1 A g^(-1)after 500 cycles)and long-term cyclability up to 1800 cycles at 2 A g^(-1).Impressively,it can deliver an outstanding rate capacity of 215 mAh g^(-1)at 10 A g^(-1),which is superior to most carbon anodes as-reported so far for PIBs.Experimental and theoretical analysis manifests that the construction of graphene/amorphous carbon interface as well as S doping enables the regulation of electronic structure and ion adsorption/transportation properties of carbonaceous material,thus accounting for the high capacity and superior rate capability of S-G@HCS composite.

Fast-Charging Sodium-Ion Batteries Enabled by Molecular-Level Designed Nitrogen and Phosphorus Codoped Mesoporous Soft Carbon

Soft carbons have attracted extensive interests as competitive anodes for fast-charging sodium-ion batteries(SIBs);however,the high-rate performance is still restricted by their large ion migration barriers and sluggish reaction kinetics.Herein,we show a molecular design approach toward the fabrication of nitrogen and phosphorus codoped mesoporous soft carbon(NPSC).The key to this strategy lies in the chemical cross-linking reaction between polyphosphoric acid and p-phenylenediamine,associated with pyrolysis induced in-situ self-activation that creates mesoporous structures and rich heteroatoms within the carbon matrix.Thanks to the enlarged interlayer spacing,reduced ion diffusion length,and plentiful active sites,the obtained NPSC delivers a superb rate capacity of 215 mAh g-1 at 10 A g-1 and an ultralong cycle life of 4,700 cycles at 5 A g^(-1).Remarkably,the full cell shows 99%capacity retention during 100 continuous cycles,and maximum energy and power densities of 191 Wh kg^(-1)and 9.2 kW kg^(-1),respectively.We believe that such a synthetic protocol could pave a novel venue to develop soft carbons with unique properties for advanced SIBs.

Ultrathin curved PdNiRu nanosheets as bifunctional catalysts for oxygen reduction and ethylene glycol oxidation

Pd-based metallic nanosheets with advanced physicochemical properties have been widely prepared and employed in various electrocatalytic reactions.However,few concerns were focused on their multiple performances in different electrocatalysis.Here,highly curved and ultrathin PdNiRu nanosheets(NSs)are developed by facile wet-chemistry strategy and exhibit excellent electrocatalytic performance toward both oxygen reduction reaction(ORR)and ethylene glycol oxidation reaction(EGOR).Owing to the synergistically structural(e.g.,ultrathin,curved,defects/steps-rich)and compositional(ternary alloy)advantages,PdNiRu NSs exhibited enhanced ORR and EGOR specific/mass activities and better stability/durability than control electrocatalysts.The specific activity(5.52 mA·cm^(−2))and mass activity(1.13 A·mg_(Pd)^(−1))of the PdNiRu NSs in ORR are 4.8 and 3.4 times as the ones of commercial Pt/C,respectively.The mass activity of PdNiRu NSs(3.86 A·mg_(Pd)^(−1))in EGOR is 2.6 times as commercial Pd/C(1.51 A·mg_(Pd)^(−1)).This study is helpful for the development of desired electrocatalysts with multi-functional application in practical fuel cells.