Li4Ti5O12 hollow macrospheres combine high tap density and excellent low-temperature performance as anode materials for Li-ion batteries

Abstract

The intrinsic low electronic and ionic conductivity severely degrades the low-temperature performance of Li4Ti5O12, especially for large sizes and high trap densities, which are essential for high active material loading. In this study, oxygen vacancy-rich Li4Ti5O12 hollow macrospheres (LTO-hm) were first prepared by a novel flame melting method. The macrospheres with a comparatively large mean diameter of 40–80 μm provide a sufficiently high tap density (1.26 g cm−3), and the unique hollow structure with ∼10 μm thick of shell reduces transfer distance of Li ions in the bulk and allows for a larger specific reactive surface. Meanwhile, the introduction of oxygen vacancies in the preparation process further improves the conductivity and Li-ion diffusion coefficient of Li4Ti5O12. Hence the prepared LTO-hm delivers excellent low-temperature performance even at a high mass loading (5 g cm−2) comparing with Li4Ti5O12 synthesized by the conventional solid-state method. It exhibits a high discharge capacity of 136.5 mAh g−1 at 1C and a capacity retention of 95.39% over 500 cycles at −20 °C. The encouraging performance provides insight into the design of Li4Ti5O12 anode for high mass loading at low temperatures.