Preparation And Performance Of Tin-based Composite Anode Materials

In this paper,composite materials such as Sn S₂/C,Na Sn₂（PO₄）₃/C（NSP/C）,and titanium and hydrogen-doped Ti-Na Sn₂（PO₄）₃/C-H（T-NSP/C-H）were synthesized by chemical methods.The synthesis process and mechanism are explored,and the composition,structure and electrochemical properties of the composite materials are systematically studied.The solvothermal method was used to directly synthesize Sn S₂/C composite materials,and the effects of different solvothermal time and different solvent ratio on the composition,structure and electrochemical performance of Sn S₂/C were investigated.The results of the study show that a suitable solvothermal time and solvent ratio are conducive to the formation of Sn S₂/C phase and improve its crystallinity;the composite material has a layered thin layer structure with a particle size of nanometers,the unique structure has a larger contact area with the electrolyte,which is beneficial to promote the transmission and conduction of lithium ions and electrons.It is used as a anode electrode material for lithium ion batteries.When the current density is 0.1 Ag^-1,the initial discharge specific capacity reaches 1305.4 m Ah g^-1;when the current density is 1 Ag^-1,the initial discharge specific capacity is 323.1m Ahg^-1.NSP/C composites were synthesized by sol-gel method and hydrothermal method respectively,and the effects of synthesis method,hydrothermal time,calcination temperature and holding time on its composition,structure and electrochemical performance were explored.The results show that the NSP/C material synthesized by the sol-gel method is composed of flakes particles embedded into each other to form a layed structure,which can increase the surface area of the electrode material,thereby faciliting the transfer of lithium ions and electrons.The NSP/C material synthesized by hydrothermal method is composed of fine particles with a size of about 100-300 nm.Increasing the hydrothermal time is beneficial to improve its crystallinity and reduce the particle size,which can effectively shorten the lithium ion during the insertion/deinsertion process and promote the transmission of lithium ions.As a anode electrode material for lithium ion batteries,the initial discharge specific capacity of NSP/C composites synthesized by the sol-gel method at a current density of 0.1 Ag^-1 reached 857.5 m Ah g^-1;the specific discharge capacity for the first time was 275.5 m Ah g^-1at 2 Ag^-1,after 200 cycles,capacity retention rate is 97.6%;the initial discharge specific capacity of hydrothermally synthesized NSP/C composite materials at 0.1 Ag^-1 is as high as 1771.1m Ah g^-1,and at 2 Ag^-1 and 5 Ag^-1 the discharge specific capacities are 606.9 m Ah g^-1 and 502.6 m Ah g^-1 respectively.After200 cycles,the discharge specific capacities are stable above 580 m Ah g^-1 and 420m Ah g^-1,and the Coulombic efficiency remains at 100%.In short,the composite material has excellent electrochemical performance.The T-NSP/C-H composite material was synthesized by sol-gel method,and the effects of different Ti content,calcination temperature and holding time on the composition,structure and electrochemical performance of T-NSP/C-H composite material were investigated.The research results show that the ultra-thin layer structure of T-NSP can shorten the solid ion and electron transmission paths in T-NSP grains and improve the rate performance;Its unique sandwich structure and Ti-doped metal nanospheres can add more active sites through lattice expansion,which is conducive to the rapid and convenient lithiation/delithiation of Li/Na mixed ions and enhanced storage of Li/Na mixed ions;H doping in hard carbon can adjust the surface functional groups of hard carbon,thereby improving its electrical conductivity,which is beneficial to charge transfer and electrode-electrolyte interaction.The T_0.01-NSP/C-H half-cell has changed to a high initial discharge specific capacity of 1246.5 m Ah g^-1 at0.1 Ag^-1,and at 2 Ag^-1 its first discharge specific capacity is 336.9 m Ah g^-1,after 200cycles the specific discharge capacity was 228.7 m Ah g^-1,and the Coulomb efficiency was still 95%after 1000 cycles.The Li/Na mixed-ion full-battery composed of after prelithiation T_0.01-NSP/C-H//PNVP has a specific discharge capacity of 177 m Ah g^-1at 2 C,which has excellent reversible capacity and rate performance.