Multifunctional Titanium Dioxide Composites As Superior Performance Anodes For Lithium Ion Batteries

Lithium ion batteries（LIBs）are widely applied in the field of consumer electronics owing to their high energy density,long cycle life,low self-discharge and no memory effect.Rational design and synthesis of advanced electrode materials are considered essential for realizing high-performance LIBs.Titanium dioxide（TiO₂）is considered to be a promising anode material with low price,abundant reserves,safety,and small volume change（<4%）during charging and discharging.However,the low Li⁺mobility and electronic conductivity restrict the development of TiO₂.In this paper,the instrinsic defects of TiO₂are modified from the following aspects to improve the lithium storage performance and the research contents and results are described as followed:（1）Carbon coated TiO₂（TiO₂-B/anatase@C-x）are prepared by using H_xTi_yO_zas precursor and the ethylene glycol as carbon source,followed by pyrolysis process with dual-phase,mesopores,carbon nanolayer and oxygen vancanies.As an anode for LIBs,a specific discharge capacity of 473.5 m Ah g^-1for TiO₂-B/anatase@C-6 is achieved at current density of 0.1 A g^-1,and which also shows excellent rate performance(179.3m Ah g^-1at the high current density of 5 A g^-1)and ultrahigh cycling stability(retain134%after 1000 cycles at 1.0 A g^-1).（2）F/Cl-TiO₂@C-T were synthesized through pyrolysis process by using TiO₂@C as a precursor and CHCl F₂as dopant.As an anode for LIBs,F/Cl-TiO₂@C-450delivers higher capacity(537.2 m Ah g^-1at current density of 0.1 A g^-1)than that of TiO₂-B/anatase@C-6,outstangding rate performance(150.2 m Ah g^-1at current density of 10.0 A g^-1),superior cycling performance(the capacity rentention of 204.8%at 1.0 A g^-1after 1000 cycles).It provides an efficient and feasible method for preparing high-rate performance Titanium-based materials with dual halogen doping.（3）Firstly,TiO₂@NPC nanocomposites were prepared by cation exchange,pyrolysis and acid etching processes.F/Cl-TiO₂@NPC-450 are synthesized through pyrolysis process by using TiO₂@NPC as a precursor and CHCl F₂dopant.As an anode for LIBs,it exihibits the discharge capacity of 998.9 m Ah g^-1at a current density of 0.1A g^-1.When the current density approach to 5 A g^-1,the discharge specific capacity can still maintain 754.9 m Ah g^-1,displaying an excellent rate performance.The results show that using CHCl F₂as the fluorine source and the chlorine source for doping is the feasible strategy to prepare the dual halogen doped titanium-based materials with high capacity.