As by-products of petroleum refining,heavy oils are characterized by a high carbon content,low cost and great variability,making them competitive precursors for the anodes of potassium ion batteries(PIBs).However,the ...As by-products of petroleum refining,heavy oils are characterized by a high carbon content,low cost and great variability,making them competitive precursors for the anodes of potassium ion batteries(PIBs).However,the relationship between heavy oil composition and potassium storage performance remains unclear.Using heavy oils containing distinct chemical groups as the carbon source,namely fluid catalytic cracking slurry(FCCS),petroleum asphalt(PA)and deoiled asphalt(DOA),three carbon nanosheets(CNS)were prepared through a molten salt method,and used as the anodes for PIBs.The composition of the heavy oil determines the lamellar thicknesses,sp^(3)-C/sp^(2)-C ratio and defect concentration,thereby affecting the potassium storage performance.The high content of aromatic hydrocarbons and moderate amount of heavy component moieties in FCCS produce carbon nanosheets(CNS-FCCS)that have a smaller layer thickness,larger interlayer spacing(0.372 nm),and increased number of folds than in CNS derived from the other three precursors.These features give it faster charge/ion transfer,more potassium storage sites and better reaction kinetics.CNS-FCCS has a remarkable K^(+)storage capacity(248.7 mAh g^(-1) after 100 cycles at 0.1 A g^(-1)),long cycle lifespan(190.8 mAh g^(-1) after 800 cycles at 1.0 A g^(-1))and excellent rate capability,ranking it among the best materials for this application.This work sheds light on the influence of heavy oil composition on carbon structure and electrochemical performance,and provides guidance for the design and development of advanced heavy oil-derived carbon electrodes for PIBs.展开更多
Transition-metal compounds have received extensive attention from researchers due to their high reversible capacity and suitable voltage platform as potassium-ion battery anodes.However,these materials commonly featur...Transition-metal compounds have received extensive attention from researchers due to their high reversible capacity and suitable voltage platform as potassium-ion battery anodes.However,these materials commonly feature a poor conductivity and a large volume expansion,thus leading to underdeveloped rate capability and cyclic stability.Herein,we successfully encapsulated ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers(NCFs)via electrospinning,carbonization,and phosphorization(antimonidization).The N-doped carbon fiber prevents the aggregation of nanoparticles,buffers the volume expansion of CoP and CoSb during charging and discharging,and improves the conductivity of the composite material.As a result,the CoP/NCF anode exhibits excellent potassium-ion storage performance,including an outstanding reversible capacity of 335mAh g^(-1),a decent capacity retention of 79.3%after 1000 cycles at 1Ag^(-1)and a superior rate capability of 148mAh g^(-1)at 5Ag^(-1),superior to most of the reported transition-metalbased potassium-ion battery anode materials.展开更多
The synthesis of atomic-scale metal catalysts is a promising but very challenging project. In this work, we successfully fabricated a hybrid catalyst of PL/Ni（OH）2 with atomic-scale Pt clusters uniformly decorated o...The synthesis of atomic-scale metal catalysts is a promising but very challenging project. In this work, we successfully fabricated a hybrid catalyst of PL/Ni（OH）2 with atomic-scale Pt clusters uniformly decorated on porous Ni（OH）2 nanowires （NWs） via a facile room-temperature synthesis strategy. The as-obtained Ptc/Ni（OH）2 catalyst exhibits highly efficient hydrogen evolution reaction （HER） performance under basic conditions. In 0.1moll-1 KOH, the Ptc/Ni（OH）2 has an onset overpotential of -0 mV vs. RHE, and a significantly low overpotential of 32 mV at a current density of 10mAcm-2, lower than that of the com- mercial 20% Pt/C （58 mV）. The mass current density data illustrated that the PL/Ni（OH）2 reached a high current den- sity of 6.34Amg^-1i at an overpotential of 50 mV, which was approximately 28 times higher than that of the commercial Pt/C （0.223Amg^-1i） at the same overpotential, proving the high-efficiency electrocatalytic activity of the as-obtained Ptc/Ni（OH）2 for HER under alkaline conditions.展开更多
Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode materi...Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode material for PIBs due to its high theoretical volumetric capacity(3763 mA h cm^−3)and relatively low working potential(−2.93 V vs.standard hydrogen electrode).However,it experiences severe capacity decay caused by a huge volume expansion of Bi when alloying with potassium.This study reports a flexible and free-standing Bi nanosheet(BiNS)/reduced graphene oxide composite membrane with designed porosity close to the expansion ratio of BiNS after charging.The controlled pore structure improves the electron and ion transport during cycling,and strengthens the structural stability of the electrode during potassiation and depotassiation,leading to excellent electrochemical performance for potassium-ion storage.In particular,it delivers a high reversible volumetric capacity of 451 mA h cm^−3 at the current density of 0.5 A g^−1,which is much higher than the previously reported commercial graphite material.展开更多
SnS has been extensively investigated as a potential anode material in potassium-ion batteries (PIBs) for its high theoretical capacity.Nonetheless,it suffers a limited cyclic lifespan owing to its poor electronic con...SnS has been extensively investigated as a potential anode material in potassium-ion batteries (PIBs) for its high theoretical capacity.Nonetheless,it suffers a limited cyclic lifespan owing to its poor electronic conductivity and huge volume expansion.This work proposed a facile approach where SnS nanocrystals are confined in the walls of hollow multichannel carbon nanofibers (denoted SnS@HMCFs) to tackle the issues above.In contrast to previous studies,impregnated ultrafine SnS nanocrystals in HMCFs compactly can increase the SnS loading number per unit area of the carbon matrix.Furthermore,the unique hollow multichannel carbon nanofibers are used as a robust carrier to uniformly distribute the SnS nanocrystals.This can significantly accelerate K;/electron transport,resulting in large specific capacity,outstanding rate performance,and steady cycling property for PIBs.High reversible capacities of 415.5 mAh g^(-1)at0.1 A g^(-1)after 300 cycles and 245.5 mAh g^(-1)at 1 A g^(-1)after 1000 cycles are retained,suggesting great potential of SnS@HMCFs as a negative electrode material for PIBs.Additionally,when the SnS@HMCF anode is assembled with the KVPO_(4)F cathode,the obtained full cell shows a large discharge capacity of165.3 m Ah g^(-1)after 200 cycles at 0.1 A g^(-1).展开更多
文摘As by-products of petroleum refining,heavy oils are characterized by a high carbon content,low cost and great variability,making them competitive precursors for the anodes of potassium ion batteries(PIBs).However,the relationship between heavy oil composition and potassium storage performance remains unclear.Using heavy oils containing distinct chemical groups as the carbon source,namely fluid catalytic cracking slurry(FCCS),petroleum asphalt(PA)and deoiled asphalt(DOA),three carbon nanosheets(CNS)were prepared through a molten salt method,and used as the anodes for PIBs.The composition of the heavy oil determines the lamellar thicknesses,sp^(3)-C/sp^(2)-C ratio and defect concentration,thereby affecting the potassium storage performance.The high content of aromatic hydrocarbons and moderate amount of heavy component moieties in FCCS produce carbon nanosheets(CNS-FCCS)that have a smaller layer thickness,larger interlayer spacing(0.372 nm),and increased number of folds than in CNS derived from the other three precursors.These features give it faster charge/ion transfer,more potassium storage sites and better reaction kinetics.CNS-FCCS has a remarkable K^(+)storage capacity(248.7 mAh g^(-1) after 100 cycles at 0.1 A g^(-1)),long cycle lifespan(190.8 mAh g^(-1) after 800 cycles at 1.0 A g^(-1))and excellent rate capability,ranking it among the best materials for this application.This work sheds light on the influence of heavy oil composition on carbon structure and electrochemical performance,and provides guidance for the design and development of advanced heavy oil-derived carbon electrodes for PIBs.
基金financially supported by the National Natural Science Foundation of China(22075147)the Natural Science Foundation of Jiangsu Province(BK20180086).
文摘Transition-metal compounds have received extensive attention from researchers due to their high reversible capacity and suitable voltage platform as potassium-ion battery anodes.However,these materials commonly feature a poor conductivity and a large volume expansion,thus leading to underdeveloped rate capability and cyclic stability.Herein,we successfully encapsulated ultrafine CoP and CoSb nanoparticles into rich N-doped carbon nanofibers(NCFs)via electrospinning,carbonization,and phosphorization(antimonidization).The N-doped carbon fiber prevents the aggregation of nanoparticles,buffers the volume expansion of CoP and CoSb during charging and discharging,and improves the conductivity of the composite material.As a result,the CoP/NCF anode exhibits excellent potassium-ion storage performance,including an outstanding reversible capacity of 335mAh g^(-1),a decent capacity retention of 79.3%after 1000 cycles at 1Ag^(-1)and a superior rate capability of 148mAh g^(-1)at 5Ag^(-1),superior to most of the reported transition-metalbased potassium-ion battery anode materials.
基金financial support from the National Natural Science Foundation of China(21425103,21673280 and 11374039)
文摘The synthesis of atomic-scale metal catalysts is a promising but very challenging project. In this work, we successfully fabricated a hybrid catalyst of PL/Ni（OH）2 with atomic-scale Pt clusters uniformly decorated on porous Ni（OH）2 nanowires （NWs） via a facile room-temperature synthesis strategy. The as-obtained Ptc/Ni（OH）2 catalyst exhibits highly efficient hydrogen evolution reaction （HER） performance under basic conditions. In 0.1moll-1 KOH, the Ptc/Ni（OH）2 has an onset overpotential of -0 mV vs. RHE, and a significantly low overpotential of 32 mV at a current density of 10mAcm-2, lower than that of the com- mercial 20% Pt/C （58 mV）. The mass current density data illustrated that the PL/Ni（OH）2 reached a high current den- sity of 6.34Amg^-1i at an overpotential of 50 mV, which was approximately 28 times higher than that of the commercial Pt/C （0.223Amg^-1i） at the same overpotential, proving the high-efficiency electrocatalytic activity of the as-obtained Ptc/Ni（OH）2 for HER under alkaline conditions.
基金This work was supported by the National Natural Science Foundation of China(51902176)China Postdoctoral Science Foundation(2018M631462)+1 种基金Guangdong Innovative and Entrepreneurial Research Team Program(2017ZT07C341)Shenzhen Municipal Development and Reform Commission and the Development and Reform Commission of Shenzhen Municipality for the development of the“Low-Dimensional Materials and Devices”Discipline.
文摘Potassium ion batteries(PIBs)with high-volumetric energy densities are promising for next-generation low-cost energy storage devices.Metallic bismuth(Bi)with a structure similar to graphite,is a promising anode material for PIBs due to its high theoretical volumetric capacity(3763 mA h cm^−3)and relatively low working potential(−2.93 V vs.standard hydrogen electrode).However,it experiences severe capacity decay caused by a huge volume expansion of Bi when alloying with potassium.This study reports a flexible and free-standing Bi nanosheet(BiNS)/reduced graphene oxide composite membrane with designed porosity close to the expansion ratio of BiNS after charging.The controlled pore structure improves the electron and ion transport during cycling,and strengthens the structural stability of the electrode during potassiation and depotassiation,leading to excellent electrochemical performance for potassium-ion storage.In particular,it delivers a high reversible volumetric capacity of 451 mA h cm^−3 at the current density of 0.5 A g^−1,which is much higher than the previously reported commercial graphite material.
基金supported by the National Natural Science Foundation of China(22179063 and 22075147)。
文摘SnS has been extensively investigated as a potential anode material in potassium-ion batteries (PIBs) for its high theoretical capacity.Nonetheless,it suffers a limited cyclic lifespan owing to its poor electronic conductivity and huge volume expansion.This work proposed a facile approach where SnS nanocrystals are confined in the walls of hollow multichannel carbon nanofibers (denoted SnS@HMCFs) to tackle the issues above.In contrast to previous studies,impregnated ultrafine SnS nanocrystals in HMCFs compactly can increase the SnS loading number per unit area of the carbon matrix.Furthermore,the unique hollow multichannel carbon nanofibers are used as a robust carrier to uniformly distribute the SnS nanocrystals.This can significantly accelerate K;/electron transport,resulting in large specific capacity,outstanding rate performance,and steady cycling property for PIBs.High reversible capacities of 415.5 mAh g^(-1)at0.1 A g^(-1)after 300 cycles and 245.5 mAh g^(-1)at 1 A g^(-1)after 1000 cycles are retained,suggesting great potential of SnS@HMCFs as a negative electrode material for PIBs.Additionally,when the SnS@HMCF anode is assembled with the KVPO_(4)F cathode,the obtained full cell shows a large discharge capacity of165.3 m Ah g^(-1)after 200 cycles at 0.1 A g^(-1).
