Synthesis Of TiO₂ Nanosheets On Cnts Matrix For The Application In Lithium Ion Battery

To satisfy the rising demand of high-end portable electronics and hybrid electric vehicles,lithium ion batteries（LIBs）with exceptional high-rate and long-life performances are highly desired.Conventionally,the working principle of LIBs follows the classical“rocking chair”mode,which mainly depends on the diffusion-controlled intercalation and deintercalation processes of lithium ions.However,the lithium ion migrations in electrode materials are often limited and irreversible,leading to poor rate performances.The latest research shows that the surface capacitive effect is very efficient in boosting the high-rate lithium storage capacity and enables fast charge and discharge processes.Accordingly,Therefore,the electrode materials with large surface area,rich interface and multi-grain boundary are expected to improve the surface capacitance and increase the battery capacity.TiO₂,which is earth abundant,economic efficient and environmental friendly,has been one of the most appealing anode materials for LIBs.Benefitting from its high working potential（～1.7 V vs.Li⁺/Li）and small volume variation（<4%）during lithium insertion and extraction,the growth of lithium dendrites and the collapse of anode structures could be effectively prevented.However,currently the electrochemical performance of TiO₂does not meet the applied requirements.Therefore,it is of practical significance to prepare TiO₂with higher density,larger reversible specific capacity and better cycling and rate performance.This paper obtains the following research results:（1）TiO₂（B）nanosheet composite was prepared by combining hydrothermal and calcining methods.In the LIBs test,it maintain a discharge capacity of 129.3 m Ah g^-1after 1000 cycles at 2 A g^-1.The specific discharge capacity of the first cycle reached1433.9 m Ah g^-1at 0.2C(1C=1675 m A g^-1),and the capacity remained at 893.7 m Ah g^-1after 100 cycles,the capacity reached 618.5 m Ah g^-1at 2C in Li-S batteries,showing good electrochemical cycling performance.（2）Titanium butoxide（TBT）were used as titanium sources to prepare precursors through hydrothermal synthesis,and calcined at the H₂S,composite materials of sulfur doped anatase TiO₂nanosheet/CNTs（S-TiO₂/CNTs）were obtained.The nanosheet is composed of tiny nanoparticles（～8 nm）which increases the number of interfaces.At 0.2 A g^-1,the discharge specific capacity of the first cylcle was 870.4m Ah g^-1,the capacity retained 311 m Ah g^-1after 100 cycles.At 2 A g^-1,the capacity is maintained at 195.5 m Ah g^-1after 700 cycles.The good electrochemical performance is attributed to:small size and S-doped.（3）The precursors were prepared by hydrothermal synthesis with TiO₂/CNTs as the base,ammonium molybdate and thiourea as the molybdenum and sulfur sources,the precursors was calcined in Ar atmosphere to obtain highly crystalline MoS₂/TiO₂/CNTs.It shows a discharge specific capacity of 1429 m Ah g^-1in the first cycle at 0.1 A g^-1.After 100 cycles,the specific discharge capacity remains 1012.2m Ah g^-1.the discharge specific capacity is maintained at 542.8 m Ah g^-1at 1 A g^-1after 500 cycles.The good electrochemical performance is attributed to:formation of Ti-O-C and Ti-O-S bond for composites.