| Nowadays,graphite is the main anode material used in lithium ion batteries,which has the advantages of good conductivity and abundant sources,but shows the disadvantages of low specific capacity(theoretical specific capacity is only375 m Ah g-1)and low safety.Ti O2 is a promising lithium battery anode material with a stable structure,high safety and low price.Its disadvantages are poor conductivity and low specific capacity,which limit its application.In order to develop an anode material with better specific capacity and safety than graphite,in this paper,based on the advantages of good structure stability and abundant sources of Ti O2,the Ti O2/black phosphorus（/BP）hybrid,N/S co-doped Ti O2/carbon-sphere hybrid,and N/S co-doped Ga2O3-Ti O2/carbon hybrid were prepared by pyrolysis and polypyrrole in-situ covering combined with pyrolysis respectively.The synthesized hybrids were characterized and their electrochemical properties were measured.The main research contents and results are as follows:Firstly,spherical nanometer titanium dioxide（b Ti O2）was prepared by hydrothermal method,and then b Ti O2/BP hybrid anode material was synthesized by calcination with b Ti O2 and BP as raw materials.At the current density of 100 m A g-1,the charge/discharge specific capacity of b Ti O2 in the the first cycle are 292 and 430 m Ah g-1 respectively,and after 100 cycles,both the charge/discharge specific capacity maintains at a stable value of 210 m Ah g-1with a capacity retention rate of 71.2%and 48.8%of the first cycle.As a comparison,the charge/discharge specific capacity of b Ti O2/BP hybrids in first cycle increased to 297 and 480 m Ah g-1 respectively,and after 100 cycles,the charge/discharge capacity maintains at a stable value of 310 m Ah g-1 with a capacity retention rate of 104.4%and 64.6%,which is 100 m Ah g-1 higher than that of b Ti O2,1.48 times that of b Ti O2,increasing by 47.6%.The results showed that the electrochemical performance of Ti O2 anode material were improved obviously after hybridized black phosphorus.In order to further improve the specific capacity of Ti O2 anode material,the nitrogen and sulfur co-doped-Ti O2/carbon microsphere hybrid was prepared,in which,black phosphorus was substituted by nitrogen and sulfur co-doped carbon.That is,the core-shell b Ti O2@PPy hybrid was prepared by in-situ polymerization with CTAB as dispersant,pyrrole as monomer and ammonium persulfate as initiator in advance,after the b Ti O2@PPy hybrid pyrolyzed,the N/S co-doped b Ti O2/carbon microspheres hybrid[（N,S）-b Ti O2@C-sphere]was obtained.At the current density of 100 m A g-1,the charge/discharge specific capacity of（N,S）-b Ti O2@C-sphere hybrid are 450 m Ah g-1 and 698 m Ah g-1,which are 153 and 218 m Ah g-1 higher than that of b Ti O2/BP hybrid respectively.After 100 cycles,the discharge specific capacity reaches 520 m Ah g-1,which is1.68 times of b Ti O2/BP hybrid,and the specific capacity retention rate is 74.5%of that of the first cycle.The hybrid material has excellent rate performance and high structural stability.For further investigate the potential of increasing the specific capacity of（N,S）-b Ti O2@C-sphere hybrid,Ga2O3 was added as heterozygous component,and（N,S）-（Ga2O3+b Ti O2）@C-Sphere hybrid was prepared as the same method as（N,S）-b Ti O2@C-sphere hybrid.The charge/discharge specific capacity of the hybrid are further increased to 861 m Ah g-1/1176 m Ah g-1,which is 1.91 and1.68 times of that of（N,S）-b Ti O2@C-sphere(450 m Ah g-1/698 m Ah g-1),respectively.However,after 100 cycles,the charge/discharge specific capacity of（N,S）-（Ga2O3+b Ti O2）@C-Sphere are only 430 m Ah g-1 and 436 m Ah g-1,which is lower than that of（N,S）-b Ti O2@C-sphere,indicating that after hybrid Ga2O3,the structural stability of（N,S）-（Ga2O3+b Ti O2）@C-Sphere decreases.Even so,the specific capacity is much higher than that of graphite and titanium dioxide. |
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