Li4Ti5O12/TiO2 dual-phase anode materials synthesized in supercritical water-methanol system and investigations on its superior electrochemical performance for lithium-ion batteries.

• Supercritical water-methanol mixture was used as reaction media. • Li 4 Ti 5 O 12 /TiO 2 dual-phase composite showed superior electrochemical properties. • Oxygen vacancy: an important role in enhancing electrochemical performance. • Pseudocapacitive effect in Li 4 Ti 5 O 12 /TiO 2 was pivotal. Li 4 Ti 5 O 12 /TiO 2 dual-phase composite compound is prepared through a supercritical fluid process with the mixture of water and methanol as solvothermal reaction media (380 °C and 31.5 MPa). When employed as anode material for lithium-ion batteries, the newly synthesized Li 4 Ti 5 O 12 /TiO 2 composite exhibits a high initial discharge capacity of 191 mA h g−1 at a current density of 100 mA g−1, and delivers a capacity retention of 90.7% even after 500 cycles at 1000 mA g−1 with the voltage window of (1.0–2.5)V. The enhanced electrochemical performance is attributed to the oxygen vacancies, the phase grain boundaries and reduced size of the Li 4 Ti 5 O 12 /TiO 2 composite particles. In addition, pseudocapacitive effect for the superior electrochemical performance of Li 4 Ti 5 O 12 /TiO 2 dual-phase composite is investigated in detail. The carbon-free Li 4 Ti 5 O 12 /TiO 2 dual-phase composite with high safety would be a promising candidate for applications in high-power lithium ion batteries. [ABSTRACT FROM AUTHOR]