Study On Improving The Electrochemical Stability Of Layered Titanium Disulfide Materials By Designing Alkali Metal Ion Electrolyt

Layered transition metal chalcogenides are widely used in electrochemical energy storage because of their excellent structural stability,fast reaction kinetics and low cost.Titanium disulfide（Ti S₂）has attracted attention because of the high conductivity,moderate potential,low requirements for oxidation and reduction resistance of electrolyte,which is an ideal cathode material for alkali metal ion batteries.Ti S₂ has been widely studied in alkali mental ion batteries such as lithium,sodium and potassium-ion batteries since Stanley Whittingham first proposed that Ti S₂ can achieve the insertion/de-insertion of Li⁺.In order to realize the high energy density of alkali mental ion battery and ensure the long-term cycle stability,at the level of electrode material design,heteroatom doping,heterstructure construction,material nanocrystallization and composite have been used to improve the stability and conductivity of it.In addition to the optimization of electrode materials,the optimization of electrolyte-electrode interface is also an important research direction to improve battery performance.The regulation of electrolyte mainly refers to the appropriate selection and proportion of solutes,solvents and additives in the electrolyte,so as to realize the effective migration of alkali metal ions at the electrode/electrolyte interface,further ensure the structural stability of the electrode in the cycle process and obtain good electrochemical performance.In this paper,the electrolyte of alkali metal/Ti S₂ battery system was designed from different angles to improve the electrochemical performance.The main research and contents and conclusions of the article are as follows:1.The crystal growth of titanium disulfide was realized by solid-state method,and the basic phase analysis was carried out by X-ray diffraction（XRD）,scanning electron microscope（SEM）,transmission electron microscope（TEM）,energy dispersive X-ray spectroscopy（EDX）and Raman spectroscopy.The results show that the titanium disulfide crystal was successfully synthesized in the experiment.2.For Ti S₂||Li battery system,the rapid and stable reversible de intercalation of Li⁺,so as to build a stable electrode/electrolyte interface are realized by the development of fluorinated electrolyte developed.In addition,the electrochemical properties of Ti S₂|Li battery system and the physicochemical properties of electrolyte was tested by cyclic voltammetry（CV）,galvanostatic intermittent titration technique（GITT）,electrochemical impedance spectroscopy（EIS）and,nuclear magnetic resonance（NMR）.The results shows that Ti S₂ material has excellent cycle performance and rate performance.At the current density of 500 m A g^-1,which maintains the specific discharge capacity of 177.26 m Ah g^-1 after 2000 cycles.Further analysis shows that this is mainly due to the rapid de-solvation of Li⁺at the interface and the formation of stable solid electrolyte interface.3.For the Ti S₂|Na battery system,high concentration ether electrolyte was used to improve the cycling stability of sodium mental batteries.Electrochemical tests were carried out by cyclic voltammetry（CV）,galvanostatic intermittent titration technique（GITT）,and electrochemical impedance spectroscopy（EIS）,which results show that the discharge specific capacity is stable at 194.01 m Ah g^-1 at the current density of 1C after 350 cycles.