Structural Design And Lithium-storage Performance Of NASICON-type NaTi₂?PO₄?₃

Aqueous lithium ion rechargeable secondary battery avoiding flammable organic electrolyte has advantages of inherent safety,high ionic conductivity,and so on,and becomes the most promising energy storage system.At present,research on cathode has made great progress.However,instability of anode affects the overall performance of battery.NaTi₂?PO₄?₃ has large pore channel,and it has broad application prospect as anode.However,NaTi₂?PO₄?₃ has poor intrinsic conductivity.In order to improve electrochemical performance,NaTi₂?PO₄?₃ with different structure was designed.1)Hierarchical N doped carbon coated NaTi₂?PO₄?₃?NTP-CN?microflower was prepared by solvothermal method.Microflower structure increases touching area between electrolyte and electrode.Carbon coating improves the stability and conductivity of materials in aqueous solution.N doping improves electronic conductivity and hydrophilicity of materials,and also forms lots of defects on carbon layer,contributing ion migration.This study shows that NTP-CN has outstanding electrochemical property?capacity retention rate: 88.8% at 6 C after 1000 cycles?.2)S/N co-doped carbon coated NaTi₂?PO₄?₃ nanoparticle?NTP@CNS?was prepared by sol-gel method.Smaller particles shorten Li ion diffusion path.Carbon coating improves the stability and conductivity of materials in aqueous solution.N doping raises electronic conductivity of electrode,and also forms lots of defects on carbon layer.S doping enlarges obviously defect degree tending to occupy defective site and edge,which achieves fast transport of ions.Electrochemical measurement shows that synthetic NTP@CNS has superb rate performance.3)N doped carbon coated NaTi₂?PO₄?₃ nanosphere was prepared by in situ dopamine polymerization.Nanosphere shortens ion migration path.N doped carbon layer improves stability and conductivity of materials in aqueous solution.NaTi₂?PO₄?₃ nanosphere with suitable coating layer exhibits excellent electrochemical performance with discharge capacities of 127.5,113.8,and 90.9 m Ah g^-1 at 0.2,3.0,and 15 C.Figure 62;Table 3;Reference 75...