Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a nove...Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a novel urchin-like NiCo2S4@mesocarbon microbead(NCS@MCMB) composite with a core–shell structure was prepared by a facile two-step hydrothermal method.The highly conductive MCMBs offered abundant adsorption sites for the growth of NCS nanoneedles,which allowed each nanoneedle to fully unfold without aggregation,resulting in improved NCS utilization and efficient electron/ion transferin the electrolyte.When applied as an electrode material for supercapacitors,the composite exhibited a maximum specific capacitance of 936 Fg-1 at 1 Ag-1 and a capacitance retention of 94% after 3000 cycles at 5 Ag-1,because of the synergistic effect of MCMB and NCS.Moreover,we fabricated an asymmetric supercapacitor based on the NCS@MCMB composite,which exhibited enlarged voltage windows and could power a light-emitting diode device for several minutes,further demonstrating the exceptional electrochemical performance of the NCS@MCMB composite.展开更多
NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)c...NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)composite is directly loaded on Ni foam by a simple one-step hydrothermal process.The conductive rGO sheets provides continuous electron pathways between NCPO flowers and Ni foam,allowing active electrochemical reactions throughout the whole electrode.This can solve the difficulty of low active material utility and small areal capacitances in the Ni foam-supported electrodes.At the same time,the rGO sheets creates large amount of mesopores within the electrode,which can ensure a highly open structure for electrolyte attachment and ion transport.Because of the positive effect of rGO in improving charge transfe r,the NiCo-phosphates can be fully involved in the electrochemical reactions with high utility,ensuring high specific capacitances(1416.7 F g^(-1)at 1 A g^(-1))and high-rate performances.Specially,the areal capacitance of the NCPO@rGO electrode can reach as large as 3.69 F cm^(-2)at 1 A g^(-1),which is among the highest ones in Ni foam supported electrodes.An asymmetric supercapacitor is then fabricated by NCPO@rGO as the positive material with attractive energy densities and power densities,further proving its excellent electrochemical performance.展开更多
Transition metal phosphides (TMPs) have been widely studied as electrode materials for supercapacitors and lithium-ion batteries due to their high electrochemical reacti on activities. The practical applicati on of TM...Transition metal phosphides (TMPs) have been widely studied as electrode materials for supercapacitors and lithium-ion batteries due to their high electrochemical reacti on activities. The practical applicati on of TMPs was gen erally hampered by their low con ductivity and large volume changes during electrochemical reactions. In this work, nitrogen-doped-carbon (NC) coated Ni2P-Ni hybrid sheets were fabricated and loaded into highly con ductive graphe ne n etwork, forming a Ni2P ?Ni@NC@G composite. The highly con ductive g raphe ne, the NC coati ng layer, and the decorated Ni nano particles in combi nation offer continu ous electro n tran sport cha nnels in the composite, resulti ng with facilitated electrode reaction kinetics and superior rate performance. Besides, the flexible graphene sheets and well-decorated Ni particles among Ni2P can effectively buffer the harmful stress during electrochemical reactions to maintain an integrated electrode structure. With these favorable features, the composite dem on strated superior capacitive and lithium storage behavior. As an electrode material for supercapacitors, the composite shows a remarkable capacitance of 2,335.5 F·g^-1 at 1 A·g^-1 and high capacitance retention of 86.4% after 2,000 cycles. Asymmetrical supercapacitors (ASCs) were also prepared with remarkable energy density of 53.125 Whk·g^-1 and power density of 3,750 Whk·g^-1. As an anode for lithium ion batteries, a high reversible capacity of 1,410 mAh·g^-1 can be delivered at 0.2 A·g^-1 after 200 cycles. Promising high rate capability was also demonstrated with a high discharge capacity of 750 mAh·g^-1 at 8 A·g^-1. This work shall pave the way for the production of other TMP materials for energy storage systems.展开更多
基金jointly supported by the National Natural Science Foundations of China(No.51572246)the Fundamental Research Funds for the Central Universities(Nos.2652017401 and 2652015425)
文摘Bimetallic Ni–Co sulfides are outstanding pseudocapacitive materials with high electrochemical activity and excellent energy storage performance as electrodes for high-performance supercapacitors.In this study,a novel urchin-like NiCo2S4@mesocarbon microbead(NCS@MCMB) composite with a core–shell structure was prepared by a facile two-step hydrothermal method.The highly conductive MCMBs offered abundant adsorption sites for the growth of NCS nanoneedles,which allowed each nanoneedle to fully unfold without aggregation,resulting in improved NCS utilization and efficient electron/ion transferin the electrolyte.When applied as an electrode material for supercapacitors,the composite exhibited a maximum specific capacitance of 936 Fg-1 at 1 Ag-1 and a capacitance retention of 94% after 3000 cycles at 5 Ag-1,because of the synergistic effect of MCMB and NCS.Moreover,we fabricated an asymmetric supercapacitor based on the NCS@MCMB composite,which exhibited enlarged voltage windows and could power a light-emitting diode device for several minutes,further demonstrating the exceptional electrochemical performance of the NCS@MCMB composite.
基金supported by the Fundamental Research Funds for the Central Universities of China(2652018291 and 2652018318)。
文摘NiCo-phosphates can deliver high specific capacitances and high electrochemical activities as pseudocapacitive electrode material for supercapacitors.In this study,The NiCo-phosphates@reduced graphene oxide(NCPO@rGO)composite is directly loaded on Ni foam by a simple one-step hydrothermal process.The conductive rGO sheets provides continuous electron pathways between NCPO flowers and Ni foam,allowing active electrochemical reactions throughout the whole electrode.This can solve the difficulty of low active material utility and small areal capacitances in the Ni foam-supported electrodes.At the same time,the rGO sheets creates large amount of mesopores within the electrode,which can ensure a highly open structure for electrolyte attachment and ion transport.Because of the positive effect of rGO in improving charge transfe r,the NiCo-phosphates can be fully involved in the electrochemical reactions with high utility,ensuring high specific capacitances(1416.7 F g^(-1)at 1 A g^(-1))and high-rate performances.Specially,the areal capacitance of the NCPO@rGO electrode can reach as large as 3.69 F cm^(-2)at 1 A g^(-1),which is among the highest ones in Ni foam supported electrodes.An asymmetric supercapacitor is then fabricated by NCPO@rGO as the positive material with attractive energy densities and power densities,further proving its excellent electrochemical performance.
基金Fundamental Research Funds for the Central Universities of China (Nos. 2652017401 and 2652015425)the National Natural Science Foundation of China (No. 51572246).
文摘Transition metal phosphides (TMPs) have been widely studied as electrode materials for supercapacitors and lithium-ion batteries due to their high electrochemical reacti on activities. The practical applicati on of TMPs was gen erally hampered by their low con ductivity and large volume changes during electrochemical reactions. In this work, nitrogen-doped-carbon (NC) coated Ni2P-Ni hybrid sheets were fabricated and loaded into highly con ductive graphe ne n etwork, forming a Ni2P ?Ni@NC@G composite. The highly con ductive g raphe ne, the NC coati ng layer, and the decorated Ni nano particles in combi nation offer continu ous electro n tran sport cha nnels in the composite, resulti ng with facilitated electrode reaction kinetics and superior rate performance. Besides, the flexible graphene sheets and well-decorated Ni particles among Ni2P can effectively buffer the harmful stress during electrochemical reactions to maintain an integrated electrode structure. With these favorable features, the composite dem on strated superior capacitive and lithium storage behavior. As an electrode material for supercapacitors, the composite shows a remarkable capacitance of 2,335.5 F·g^-1 at 1 A·g^-1 and high capacitance retention of 86.4% after 2,000 cycles. Asymmetrical supercapacitors (ASCs) were also prepared with remarkable energy density of 53.125 Whk·g^-1 and power density of 3,750 Whk·g^-1. As an anode for lithium ion batteries, a high reversible capacity of 1,410 mAh·g^-1 can be delivered at 0.2 A·g^-1 after 200 cycles. Promising high rate capability was also demonstrated with a high discharge capacity of 750 mAh·g^-1 at 8 A·g^-1. This work shall pave the way for the production of other TMP materials for energy storage systems.
