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.

Monodispersed SWNTs Assembled Coating Layer as an Alternative to Graphene with Enhanced Alkali-ion Storage Performance

Graphene coating is commonly used to improve the performance of electrode materials,while its steric hindrance effect hampers fast ion transport with compromised rate capability.Herein,a unique single-walled carbon nanotubes(SWNTs)coating layer,as an alternative to graphene,has been developed to improve the battery behavior of iron-based anodes.Benefiting from the structure merits of mesoporous SWNTs layer for fast electron/ion transport and hollow Fe_(3)O_(4) for volume accommodation,as-prepared Fe_(3)O_(4)@SWNTs exhibited excellent lithium storage performance.It delivers a high capacity,excellent rate capability,and long lifespan with capacities of 582 mA·h·g^(-1) at 5 A·g^(-1) and 408 mA·h·g^(-1) at 8 A·g^(-1) remained after 1000 cycles.Such performance is better than graphene-coated Fe_(3)O_(4) and other SWNT-Fe_(3)O_(4) architectures.Besides,SWNTs coating is also used to improve the sodium and potassium storage performance of FeSe_(2).The kinetics analysis and ex-situ experiment further reveal the effect of SWNTs coating for fast electron/ion transfer kinetics and good structure stability,thus leading to the superior performance of SWNTs-coated composites.

Boosting Stable and Fast Potassium Storage of Iron Sulfide through Rational Yolk-Shell Design and Ni Doping

Metal sulfides have been regarded as promising anodes for potassium-ion batteries(PIBs)due to their high theoretical capacities,while the performance is limited by their intrinsic poor conductivity and large volume fluctuation during the insertion/extraction of large potassium ion.Herein,the battery performance of iron sulfide anode is significantly enhanced through yolk-shell(Y-S)structure design and nickel doping,aiming to realize good structure stability and superior electron/ion transportation.For potassium storage,as-prepared Y-S Ni-FeS_(2)@C shows excellent cyclic performance and sustains high capacities of 328 mA h g^(-1)after 100 cycles at 0.2 A g^(-1)and 226 mA h g^(-1)after 1000 cycles at 1 A g^(-1).Especially,it displays a superior rate capacity of 200 mA h g^(-1)at 20 A g^(-1),higher than that of Y-S FeS_(2)@C and most as-reported metal sulfide anodes for PIBs.The experimental analysis and theoretical calculation illuminate the effect of Ni-doping on decreasing the particle size of iron sulfide and enhancing the ion/electron transport ability,thus accounting for the exceptional rate capability of Y-S Ni-FeS_(2)@C composite.