Influence of synthesis conditions on crystal formation and electrochemical properties of TiO2(B) particles as anode materials for lithium-ion batteries

TiO2(B) particles as the anode material for lithium-ion batteries were synthesized from three kinds of layered alkali titanates Na2Ti3O7, K2Ti4O9 and Cs2Ti5O11 via H+ ion-exchange followed by heating under several conditions in order to clarify the effect of synthesis conditions on crystal formation and electrochemical properties. Phase formation and crystal structure were analyzed by X-ray diffraction, inductively coupled plasma analysis, and transmission electron microscopy. Reducing of residual alkali cations in the intermediates with ion-exchanging for 2 weeks led to relative high crystallinity which is suitable for smooth migration of lithium ions and has low reactivity with a practical electrolyte. The primitive cell volume of TiO2(B) increased with decreasing heat-treatment temperature of the intermediates. A primitive cell volume of 0.300 nm3 in TiO2(B) structure, which was successfully obtained from the precursor K2Ti4O9 by heating the intermediate at 350 °C for 2 h, causes an expanding of the lithium pathways and storage sites and had a high reversible capacity of 253.1 mA h g−1 close to that of TiO2(B) nanopaticles. This TiO2(B) also showed good cycle performance with the reversible capacity after 200 cycles remaining 95% of the initial capacity, using a practical electrolyte such as LiPF6 in a solution of ethylene carbonate and diethyl carbonate. Consequently, synthesis conditions of H+ ion-exchange time and heat-treatment temperature should be carefully optimized to obtain the large reversible capacity and stable cycle performance of TiO2(B) synthesized from the layered alkali titanates via the H+ ion-exchange process.