High-loaded nanobelt-array/nanobelt-microsphere multilayer Li4Ti5O12 self-supported on Ti foils for high-performance lithium ion battery

A high-loaded porous nanobelt-constructed multilayer hierarchical Li4Ti5O12 nanostructure (NBMH-LTO) is prepared via a hydrothermal process with the presence of NaF. This novel NBMH-LTO contains a nanobelt array layer directly grown on the Ti substrate and upper hollow microsphere-layers consisting of nanobelts. The self-standing Li4Ti5O12 nanobelts on conductive Ti foil can be directly used as anode in flexible and foldable lithium ion batteries without using conductive additives or binders. Furthermore, N-doped NBMH-LTO (NBMHNLTO) electrode is successfully obtained via a simple vapor-solid reaction process between NBMH-LTO and NH3, and it exhibits a high areal capacity of 0.71 mAh cm−2 at 0.1 mA cm−2 and excellent rate/cyclic performance. Additionally, the NBMHNLTO electrode also displays excellent performance at low temperature, after 100 cycles at -20 °C (1 mA cm−2), the capacity retention rate can reach to 98.6%. The enhanced performance of NBMHNLTO can be attributed to its high active materials load benefited from the new synthesis strategy, good electronic connection profited from the unique 3D network of nanbelts, and the further improved electron conductivity due to the presence of Ti3+in nanobelts.