Understanding the formation of ultrathin mesoporous Li4Ti5O12 nanosheets and their application in high-rate, long-life lithium-ion anodes.

Two-dimensional nanosheet-like materials with ultra-small thickness and uniform porous structures hold great promise for high-rate and long-life lithium-ion batteries. In this work, pure ultrathin mesoporous Li4Ti5O12 nanosheets are fabricated by combining a facile solvothermal synthesis with a calcination process. The detailed formation mechanism of ultrathin mesoporous Li4Ti5O12 nanosheets is systematically investigated, which identified the key factors that control the structure development. The unique structural features including ultra-small thickness, large specific surface area and uniform mesoporous structures endow such materials with effective charge transport channels, abundant reaction active sites and inner-plain void space for improved structural stability. As a result, the ultrathin mesoporous Li4Ti5O12 nanosheets offer nearly theoretical capacity (174 mA h g-1 at 1 C), very high rate capability (e.g., 145 mA h g-1 at 50 C), and excellent cycling stability (95% capacity retention after 2500 cycles at 20 C), suggesting their great promise as anode materials for ultrahigh-power and long-life lithium-ion batteries.