Electrochemical Property of Particle-size Controlled H2Ti12O25 as a Negative Electrode Material for Lithium-ion Battery

We have successfully prepared the particle-size controlled H2Ti12O25 by soft chemical synthetic technique using the ball-milled and annealed Na2Ti3O7 as a starting compound. In this synthetic route, we first prepared the particle-size controlled Na2Ti3O7 by ball-milling and subsequent annealing at 873–1073 K. Then, H2Ti3O7 was prepared by Na+/H+ ion-exchange reaction using HCl solution, and H2Ti12O25 was synthesized by heating H2Ti3O7 at 533 K. The initial discharge capacity of the H2Ti12O25 sample thus obtained was achieved to be 255 mAh g−1, which was higher than those previously reported for H2Ti12O25 samples, while initial irreversible capacity also increased together with the amounts of smaller particles.