Synthesis and electrochemical performance of three-dimensional ordered hierarchically porous Li4Ti5O12 for high performance lithium ion Batteries

In this work, a three-dimensional ordered hierarchically porous (3DOHP) Li4Ti5O12 that possesses inner-particle mesopores resulting from a soft template method and a three-dimensional ordered macroporous (3DOM) Li4Ti5O12 using polystyrene spheres as a hard template have been synthesized. Both 3DOM Li4Ti5O12 and 3DOHP Li4Ti5O12 have ordered macropores and interconnected skeletons with a regular periodicity revealed by SEM and TEM observations. The specific surface area of 3DOHP Li4Ti5O12 is up to 135 m2 g−1 which is much higher compared with that of 3DOM Li4Ti5O12 because of the existence of inner-particle mesopores. Attributed to the higher surface area and smaller crystal grain size, more excellent cycle performance and rate capability are obtained for 3DOHP Li4Ti5O12 compared to 3DOM Li4Ti5O12. In addition, the hierarchically porous structure of 3DOHP Li4Ti5O12 can meet rapid insertion and deinsertion of lithium ion even at extremely high rate. It is apparent that 3DOHP Li4Ti5O12 has a lower total resistance and faster Li+ diffusion coefficient compared to 3DOM Li4Ti5O12 according to electrochemical impendence spectroscopy analysis.