Synthesis Of Titanium Oxide (Telluride/Selenide) Solids For Separator Modification In Lithium-Sulfur Batteries

Lithium-sulfur（Li-S）batteries,with their high theoretical specific energy(2600Wh kg^-1),low cost,and environmental friendliness,are considered as one of the most promising candidate systems to meet high specific energy demands.At present,there are still some problems waiting to be solved,among which the most important ones are the shuttle effect of polysulfide,slow conversion kinetics of lithium-sulfur batteries,instability of lithium metal anode,etc.The separator is one of the core components of the battery,and the modification on the positive side of the separator can effectively inhibit the shuttle effect of polysulfide,improve the conversion kinetics of lithium sulfur battery,and improve the stability of lithium metal anode.In this paper,TiO₂@MoS₂ composite materials were synthesized by hydrothermal method,and TiTe₂and TiSe₂ were synthesized by high-temperature solid-state method,respectively,and coated on the positive electrode side diaphragm.The application of their modified diaphragm in lithium-sulfur batteries was explored,and the electrochemical performance of the battery was studied.The main research results are as follows:TiO₂@MoS₂ composite solids were synthesized by hydrothermal method and applied to separator modification.At a current density of 0.2C,the initial capacity of the battery was 1100 m Ah g^-1,and after 100 cycles,the specific capacity remained 682m Ah g^-1,which improved the reaction kinetics of the battery.TiTe₂ was synthesized by a simple high-temperature solid-phase method and applied to separator modification.At a current density of 0.2C,the initial capacity of the battery was 1197 m Ah g^-1,and after 100 cycles,the specific capacity remained 787m Ah g^-1,which played a catalytic role.TiSe₂ was synthesized by a high-temperature solid-phase method and used for separator modification.At a current density of 0.2C,the initial capacity of the battery with the TiSe₂ modified separator was 1480 m Ah g^-1,and after 100 cycles,the specific capacity remained 779 m Ah g^-1,which effectively suppressed the shuttle effect of polysulfides.Compared with TiO₂@MoS₂ composite solid and TiTe₂,TiSe₂ modified separator has the most significant effect on improving the electrochemical performance of lithium sulfur batteries,which provides a new idea for the development of new materials for separator modification of lithium sulfur batteries.