The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparative...The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparatively poor rate performance and cycle stability.Herein,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous co-doping.The as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without templates.The obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g^(-1)at a current density of 0.1A·g^(-1)and a good long-term cycle performance(96.1%capacity retention after 800 cycles at 0.5 A·g^(-1)).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P co-doping.Ex-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer space.The suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.展开更多
Hollow structures are commonly used to alleviate the mechanical stress on electrode materials and to provide more active sites in potassium-ion batteries(KIBs).Nevertheless,the excessive internal voids within these st...Hollow structures are commonly used to alleviate the mechanical stress on electrode materials and to provide more active sites in potassium-ion batteries(KIBs).Nevertheless,the excessive internal voids within these structures significantly reduce the packing density of particles,resulting in a relatively low volumetric energy density of the fabricated electrodes,which is undesirable for practical use.We designed a hollow mesoporous carbon bowl embedded with ultrafine bis(selanylidene)iron(FeSe 2)nanocrystals(FeSe 2@HMCB)via a controllable impregnation method and subsequent selenization pro-cess for high-performance KIBs.The as-obtained FeSe 2@HMCB can inherit the advantages of conventional hollow carbon-based composites,such as alleviation of volume variation in active materials,abundant ion storage sites,and high electrical conductivity.Simultaneously,the bowl structure has a higher pack-ing density than the conventional hollow structure,resulting in a significant increase in the volumet-ric energy density of the fabricated electrodes.Because of these advantages,the FeSe 2@HMCB exhibits a high,stable reversible capacity of 326 mA h g^(-1) even after 1000 cycles at 0.5 A g^(-1),and excellent rate capacities(182 mA h g^(-1) at 3.0 A g^(-1)).Compared with the hollow structured counterpart,the vol-umetric capacity(mA h cm−3)of FeSe 2@HMCB increased by 60%.Furthermore,a full cell consisting of FeSe 2@HMCB//Prussian blue(PB)exhibits excellent electrochemical performance(99 mA h g^(-1) after 100 cycles at 0.1 A g^(-1)).展开更多
基金financially supported by the National Research Foundation of Korea(NRF)from Korean government(MSIT,Korea)(No.2023R1A2C1005459)the Materials/Parts Technology Development Program from the Ministry of Trade,Industry,and Energy(MOTIE,Korea)(No.20019205)。
文摘The larger ionic radius of potassium ions than that of lithium ions significantly limits the accomplishment of rapid diffusion kinetics in graphite electrodes for potassium-ion batteries(PIBs),resulting in comparatively poor rate performance and cycle stability.Herein,we report a high-rate performance and cycling stability amorphous carbon electrode achieved through nitrogen and phosphorous co-doping.The as-prepared N,P co-doped carbon electrodes have distinct 3D structures with large surface areas,hierarchical pore architectures,and increased interlayer spaces resulting from the direct pyrolysis of supramolecular self-assembled aggregates without templates.The obtained electrode N3P1 exhibits a reversible specific capacity of 258 m Ah·g^(-1)at a current density of 0.1A·g^(-1)and a good long-term cycle performance(96.1%capacity retention after 800 cycles at 0.5 A·g^(-1)).Kinetic investigations show that the N3P1 electrode with the welldeveloped porous structure and large number of surface defects exhibits capacitive-driven behavior at all scan rates,which may be attributed by N and P co-doping.Ex-situ transmission electron microscopy analyses in the fully discharged and charged states demonstrate structural stability and reversibility owing to the expanded interlayer space.The suggested synthesis approach is simple and effective for producing heteroatom-doped carbon materials for PIBs and other advanced electrochemical energy storage materials.
基金supported by the National Research Foundation of Korea (NRF)grant funded by the Korean government (MSIT) (No.2020R1C1C1003375)the Material Technology Development Program (20022507)funded by the Ministry of Trade,Industry&Energy (MOTIE,Korea).
文摘Hollow structures are commonly used to alleviate the mechanical stress on electrode materials and to provide more active sites in potassium-ion batteries(KIBs).Nevertheless,the excessive internal voids within these structures significantly reduce the packing density of particles,resulting in a relatively low volumetric energy density of the fabricated electrodes,which is undesirable for practical use.We designed a hollow mesoporous carbon bowl embedded with ultrafine bis(selanylidene)iron(FeSe 2)nanocrystals(FeSe 2@HMCB)via a controllable impregnation method and subsequent selenization pro-cess for high-performance KIBs.The as-obtained FeSe 2@HMCB can inherit the advantages of conventional hollow carbon-based composites,such as alleviation of volume variation in active materials,abundant ion storage sites,and high electrical conductivity.Simultaneously,the bowl structure has a higher pack-ing density than the conventional hollow structure,resulting in a significant increase in the volumet-ric energy density of the fabricated electrodes.Because of these advantages,the FeSe 2@HMCB exhibits a high,stable reversible capacity of 326 mA h g^(-1) even after 1000 cycles at 0.5 A g^(-1),and excellent rate capacities(182 mA h g^(-1) at 3.0 A g^(-1)).Compared with the hollow structured counterpart,the vol-umetric capacity(mA h cm−3)of FeSe 2@HMCB increased by 60%.Furthermore,a full cell consisting of FeSe 2@HMCB//Prussian blue(PB)exhibits excellent electrochemical performance(99 mA h g^(-1) after 100 cycles at 0.1 A g^(-1)).