| In recent years,due to the growing serious problems of environmental pollution and energy shortage,green new energy sources such as lithium-ion batteries have been widely used in people's daily lives.Compared to lithium-ion batteries,sodium-ion batteries have attracted much attention due to their rich raw materials,low cost,and the similar physical and chemical properties of sodium and lithium.Additionally,lithium-sulfur batteries have a higher theoretical capacity(1675 m Ah g-1),energy density(2600 Wh kg-1)and rich sulfur content in the earth's crust,making them more beneficial to large-scale power storage.Carbon materials are widely used in the fields of energy storage due to their outstanding advantages such as low cost,easy accessible raw materials,and good electrical conductivity.This paper studies different heteroatom-doped carbon materials and applies them to sodium-ion batteries and lithium-sulfur batteries.At the same time,the internal relationship between its composition and structure and electrochemical performance is studied.The main elements of the work is as follows:?1?Preparation and sodium storage properties of sulfur-doped carbon composite with neuron-like three-dimensional network structure?3DSC-700?:a neuron-like 3D network structure carbon with S-doped and metal particles decoration was fabricated via an in-situ polymerization and high-temperature calcination using thiophene?Th?and pre-prepared ZIF-8/ZIF-67 as precursors.When 3DSC-700 was used as an anode electrode material applied in sodium-ion batteries?SIBs?,it exhibits a reversible capacity of 225m Ah g-1 after 3000 cycles at 5000 m A g-1.In the sodium-ion full cell tests,at a current density of 100 m A g-1,a high specific capacity of 229.64 m Ah g-1 can be maintained after50 cycles.The excellent performance of 3DSC-700 is mainly due to the synergistic effect of the special three-dimensional network structure,sulfur doping and metal particle modification,which makes 3DSC-700 have a higher capacity and ultra-long cycle stability.In addition,S doping can endow carbon-based material with enhanced Na adsorption energies,more Na atom accommodation and lower diffusion energy barrier.?2?Preparation and sodium storage properties of N and P co-doped carbon tubes?NPC?:a unique hollow structure of N and P co-doped carbon tubes was synthesized using pyrrole monomer and phytic acid as raw materials,through a combination of chemical polymerization and thermal treatment processes.When applied as an anode electrode of SIBs,it delivers a high reversible capacity of 172 m Ah g-1 at 10,000 m A g-1,and an ultra-stable capacity of 180.3 m Ah g-1 after 3000 cycles at 5000 m A g-1.The unique hollow tube structure and the co-doping of N and P endow the NPC electrodes with excellent electrochemical performance.?3?Co-modified corn husk-derived carbon composite graphene oxide modified lithium-sulfur battery separator?Co-3DC-r GO/PP?:The Co-3DC-r GO were prepared using corn husk,ZIF-67,and graphene as precursors,through solvothermal and heat treatment processes,which was then coated on PP separator to obtain the Co-3DC-r GO/PP modified separator.When applied as the separator of lithium-sulfur battery,it can maintain a high reversible capacity of 710 m Ah g-1 after 150 cycles at 0.5 C.Co-3DC-r GO/PP modified separator can obtain a stable reversible capacity of 516 m Ah g-1 after500 cycles at 1 C.Its excellent performance is mainly attributed to the strong adsorption capacity between the high specific surface carbon in Co-3DC-r GO composite and the lithium polysulfide,and the catalytic conversion ability of the Co metal nanoparticles to lithium polysulfide during the electrochemical reaction.In addition,the r GO in the composite can provide an excellent conductive network,and the r GO also can absorb polysulfide and act as an additional barrier to prevent the polysulfide passing through the PP separator. |
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