Electrochemical In Situ Formation of a Stable Ti-Based Skeleton for Improved Li-Storage Properties: A Case Study of Porous CoTiO3 Nanofibers.

Abstract

Bimetallic transition-metal oxides, which exhibit superior electrochemical properties compared with pristine single-metal oxides, have recently become a topic of significant research interest for applications in lithium-ion batteries (LIBs). Herein, we report a simple and scalable electrospinning method to synthesize porous CoTiO3 nanofibers as the precursor for nanostructured bimetallic transition-metal oxides formed electrochemically in situ. This strategy ensures uniform mixing and perfect contact between two constituent transition-metal oxides during the lithiation/delithiation process. Furthermore, CoTiO3 nanofibers based on ultrafine CoTiO3 nanocrystals are interconnected to form a nano/microstructured 3D network, which ensures the high stability of the in situ formed structure composed of bimetallic transition-metal oxides, and also fast ion/electron transfer and electrolyte penetration into the electrode. Electrochemical measurements revealed the excellent lithium storage (647 mAh g-1 at 0.1 Ag-1 ) and retention properties (600 mAh g-1 at 1 Ag-1 after 1200 cycles) of the CoO/TiO2 electrode. Moreover, the electrochemical reaction mechanism was explored by using ex situ X-ray photoelectric spectroscopy and cyclic voltammetry tests, which confirmed the two-phase reaction processes in the electrodes. These results clearly validate the potential of CoTiO3 with a unique nano/microstructured morphology as the precursor for a bimetallic transition-metal oxide for use as the anode material for long-life LIBs.