Controllable defect engineering enhanced bond strength for stable electrochemical energy storage

Abstract

Transition metal dichalcogenides (TMDs) with layered structure are regarded as a potential electrode material for high-performance energy storage devices, while intrinsic low electrical conductivity causes poor electrochemical performance. As we know, the change of atomic structure for TMDs can lead to the improvement of electrochemical properties. In this work, defect chemistry is employed to achieve this purpose. TiS 2 as a typical electrode material is chosen to complete the study of controllable defect engineering. Theoretical calculations and experimental analysis confirm that concentration and species of defects can be controlled via adjusting the experimental conditions. A series of concentrations of sulfur vacancies are introduced in TiS 2 by annealing methods. The introduction of sulfur vacancies enhances bond strength of Ti-S bonds near the defect area and improves electronic structure. Benefiting from the positive effect of sulfur vacancies, the electrochemical characteristics of TiS 2 are greatly optimized, including cycle ability and dynamic characteristics. In addition, it is found that the improvement of electrochemical performance is closely related to the concentration of defects. These results reveal that controllable defect engineering may be a fascinating strategy to promote the advancement of TMDs in energy storage application. • Defect engineering can be controlled by changing the experimental conditions. • S vacancy enhances the bond strength of Ti-S bonds. • Defect concentration is related to electrochemical performance. • The capacity retention of TiS 2−x is twice that of the pristine one after 500 cycles. • S vacancy can enhance electronic conductivity and promote ions transport.