Phase-dependent performance of lotus-root shaped TiO2 anode for lithium-ion batteries (LIBs)

Abstract

We had reported the lotus-root shaped meso-/macroporous TiO2 (LR-TiO2) for the photoanode of DSSCs and also the synergistic interfacial electron transfer of coexisting anatase and rutile phases in a mesoporous TiO2 particle. Thus, we were to investigate phase-dependent performance of LR-TiO2 as an anode for LIB comparable to DSSCs mechanistically, whose crystalline phase was controlled by simply varying the calcination temperature. SEM measurements showed the unchanged morphological characteristics of columnar macroporous channels favorable for Li+ supply regardless of the calcination temperature. However, anatase- and rutile-rich phases were confirmed by PXRD measurements for LR-TiO2 calcined at 450 °C (LR-TiO2-450) and 700 °C (LR-TiO2-700), respectively. The capacity of the LR-TiO2-450 anode was 120 mAh g-1 and the capacity of LR-TiO2 decreased with the increase of calcination temperature. It is basically attributed to a better electrical conductivity of anatase to rutile and loss of surface area due to a poor stacking of larger rod-like rutile granules compared to smaller spherical anatase ones. However, we could not specify the expected synergistic effect of mixed phase in LR-TiO2-550 because the resistance of electron transfer is not significant compared to that of Li+ transfer based on EIS measurements. Correspondingly, high rate performance showed the higher capacity decrease as the C-rate increased.