Nickel sulfides are promising anode materials for lithium-ion batteries(LIBs)due to their high theoretical capacities but suffer from a sluggish kinetic process and poor structural stability.Herein,we develop a ration...Nickel sulfides are promising anode materials for lithium-ion batteries(LIBs)due to their high theoretical capacities but suffer from a sluggish kinetic process and poor structural stability.Herein,we develop a rationally integrated strategy for the construction of a S/N co-doped carbon-coated NiS/Cu_(2)S composite(NiS/Cu_(2)S@N/S–C)via a convenient one-step calcination process.Copper can be formed in situ during the lithiation process of the conversion reaction after combining nano-scale nickel sulfide with proper cuprous sulfide,which is conducive to increasing the conductivity,promoting the reversible conversion of the discharge product Li_(2)S,and suppressing the dissolution of polysulfides,leading to the superior kinetic property and structural stability of the electrode.Notably,the S/N co-doped carbon coating with polar C–S or C–N bonds not only enhances the transfer of electrons and ions but also inhibits coarsening,agglomeration of particles and dissolution of polysulfides during lithiation.Furthermore,density functional theory(DFT)calculations show that heterogeneous atomic doping of N and S can enhance the adsorption behavior of carbon sheets to NiS,Cu_(2)S and intermediate discharge products in LIBs,further demonstrating an improvement of lithium storage capability and cycling stability due to the S/N codoped carbon coating.As a result,NiS/Cu_(2)S@N/S–C possesses a considerable rate capacity of 511.7 mA h g^(−1) at 3 A g^(−1),and an outstanding stable capacity of 771.7 mA h g^(−1) at 2 A g^(−1) with a high retention rate of 98%after 1800 cycles.NiS/Cu_(2)S@N/S–C shows remarkable comprehensive performance when compared with most reported nickel sulfide anode materials.This strategy predigests the tedious process of sulfurization and carbon encapsulation and would be of great significance to design nickel sulfide anodes with excellent lithium storage performance.展开更多
A novel silicon-carbon composite with a 3D pore-nest structure denoted as Si@SiO_(x)/CNTs@C was prepared and studied.The results showed that agglomeration of nano-silicon particles is effectively inhibited by the addi...A novel silicon-carbon composite with a 3D pore-nest structure denoted as Si@SiO_(x)/CNTs@C was prepared and studied.The results showed that agglomeration of nano-silicon particles is effectively inhibited by the addition of a surfactant;meanwhile,surfactant pyrolytic carbon(SPC)and a relatively dense SiO_(x) mechanical binding layer on the surface of Si magnificently restrain the volume expansion during the lithiation process and are conducive to the formation of a stable SEI film.In addition,a 3D electron pathway was constituted by CNTs,graphite and SPC on the surface of Si to enhance the conductivity.The results showed that the capacity of the Si@SiO_(x)/CNTs@C composite anode can be maintained at above 1740 mA h g^(-1) at a current density of 0.42 A g^(-1) after 700 cycles without capacity loss compared to the initial charge capacity,which indicated the excellent cycle performance of the composite material.Furthermore,a rule of thumb has been perceived by means of CV,cell charging/discharging measurements and their differential capacity analyses,which is characteristic of an electrode made of silicon as an active material.The finding contributes to the in-depth comprehension and general elucidation of the degradation mechanism of Si-based anode materials.展开更多
基金supported by Training Program of Major Basic Research Project of Provincial Natural Science Foundation of Guangdong(2017B030308001)the Research Fund of Guangdong-Hong Kong-Macao Joint Laboratory for Intelligent Micro-Nano Optoelectronic Technology(No.2020B1212030010)+1 种基金the Fundamental and Applied Fundamental Funds of Guangdong-Regional Joint Fund for Youth Project(2020A1515110980)National Natural Science Foundation of China(No.52101254).
文摘Nickel sulfides are promising anode materials for lithium-ion batteries(LIBs)due to their high theoretical capacities but suffer from a sluggish kinetic process and poor structural stability.Herein,we develop a rationally integrated strategy for the construction of a S/N co-doped carbon-coated NiS/Cu_(2)S composite(NiS/Cu_(2)S@N/S–C)via a convenient one-step calcination process.Copper can be formed in situ during the lithiation process of the conversion reaction after combining nano-scale nickel sulfide with proper cuprous sulfide,which is conducive to increasing the conductivity,promoting the reversible conversion of the discharge product Li_(2)S,and suppressing the dissolution of polysulfides,leading to the superior kinetic property and structural stability of the electrode.Notably,the S/N co-doped carbon coating with polar C–S or C–N bonds not only enhances the transfer of electrons and ions but also inhibits coarsening,agglomeration of particles and dissolution of polysulfides during lithiation.Furthermore,density functional theory(DFT)calculations show that heterogeneous atomic doping of N and S can enhance the adsorption behavior of carbon sheets to NiS,Cu_(2)S and intermediate discharge products in LIBs,further demonstrating an improvement of lithium storage capability and cycling stability due to the S/N codoped carbon coating.As a result,NiS/Cu_(2)S@N/S–C possesses a considerable rate capacity of 511.7 mA h g^(−1) at 3 A g^(−1),and an outstanding stable capacity of 771.7 mA h g^(−1) at 2 A g^(−1) with a high retention rate of 98%after 1800 cycles.NiS/Cu_(2)S@N/S–C shows remarkable comprehensive performance when compared with most reported nickel sulfide anode materials.This strategy predigests the tedious process of sulfurization and carbon encapsulation and would be of great significance to design nickel sulfide anodes with excellent lithium storage performance.
基金financially supported by Jinan Science and Technology Research Grant(No.201401274)Jining 511 Recruitment Program of Global Experts(No.2012N130),P.R.China.
文摘A novel silicon-carbon composite with a 3D pore-nest structure denoted as Si@SiO_(x)/CNTs@C was prepared and studied.The results showed that agglomeration of nano-silicon particles is effectively inhibited by the addition of a surfactant;meanwhile,surfactant pyrolytic carbon(SPC)and a relatively dense SiO_(x) mechanical binding layer on the surface of Si magnificently restrain the volume expansion during the lithiation process and are conducive to the formation of a stable SEI film.In addition,a 3D electron pathway was constituted by CNTs,graphite and SPC on the surface of Si to enhance the conductivity.The results showed that the capacity of the Si@SiO_(x)/CNTs@C composite anode can be maintained at above 1740 mA h g^(-1) at a current density of 0.42 A g^(-1) after 700 cycles without capacity loss compared to the initial charge capacity,which indicated the excellent cycle performance of the composite material.Furthermore,a rule of thumb has been perceived by means of CV,cell charging/discharging measurements and their differential capacity analyses,which is characteristic of an electrode made of silicon as an active material.The finding contributes to the in-depth comprehension and general elucidation of the degradation mechanism of Si-based anode materials.
