Negative electrode material for lithium ion batteries containing surface-fluorinated b-type titanium oxide powder, method for producing same, and lithium ion battery using same

The present invention addresses the problem of providing a B-type titanium oxide (TiO2(B)) powder which can be suitable for use as a negative electrode material for lithium ion batteries by improving the charge and discharge characteristics and the rate characteristics of the B-type titanium oxide powder by a simple treatment. A surface-fluorinated B-type titanium oxide powder is obtained by reacting a B-type titanium oxide powder in a fluorine-containing gas atmosphere at 0-200 DEG C for 1 minute to 10 days. The fluorination treatment is preferably carried out at 0.01-2 atm. It is preferable to use, as the fluorine-containing gas, a gas that contains a fluorine compound, said gas being selected from among a fluorine (F2) gas, a nitrogen trifluoride (NF3) gas, a perfluorotrimethylamine (N(CF3)3) gas, a chlorine trifluoride (ClF3) gas and the like.