Heterosructure Modulated Carbon Materials For Lithium-Sulfur Battery

Lithium-sulfur(Li/S)batteries have the advantages of high energy density and low cost,and is expected to become one of the next generation of electrochemical energy storage systems to meet the demand of new energy batteries.However,compared with commercial lithium-ion batteries,the practical application of lithium-sulfur batteries faces many challenges:low sulfur utilization,shuttle effect caused by soluble lithium polysulfide,slow lithium-sulfur conversion kinetics and lithium dendrites.In order to solve the above problems,heterostructured modulated carbon materials were used to design carbon nitride(C₃N₄)/Carbon sustainable material sulfur cathode carrier,titanium nitride-niobium carbide/carbon(TiNbNC)nanofibers to accelerate multi-sulfide lithium conversion membrane reactor,and TiNbNC nanofibers to induce uniform nucleation and deposition of lithium.The main research contents are as follows:Firstly,C₃N₄ was grafted into discarded coal briquets and loofah pulp derived carbon materials to construct C₃N₄/Carbon sustainable materials for the positive electrode of lithium-sulfur batteries.The initial specific capacity was 1269.8 m A h g^-1(0.05 C),and the capacity retention rate was 88.8%after 120 cycles(0.5 C),and the coulomb efficiency was 98.4%.Secondly,TiNbNC/PAN precursors were prepared by electrospinning and high temperature curing technology to obtain TiNbNC core-shell nanofibers,which were used in polysulfide conversion membrane reactor.The 3C-rate discharge capacity reaches 845 m A h g^-1,200 times.The cycle retention rate of the battery is 93.4%.Finally,TiNbNC nanofibers are used to regulate the nucleation and growth of lithium,reduce the local current density of lithium anode,and inhibit the dendrite of lithium.It provides a new way to develop high performance lithium metal anode protection based on lightweight one-dimensional framework.