2, Texas A&M University, College Station, Texas, United States
The electrochemical performance of transition metal oxides (TMOs) electrodes for lithium-ion batteries (LIBs) has been hindered by their instability in electrochemical performance and lack of durability. In this research, a novel hierarchical micro-electrode for LIBs is successfully designed and fabricated. Anatase TiO2 nanoparticles of ~100 nm are synthesized through a simple one-step wet-chemical method at elevated temperature. The Cu/Ni current collector with vertically-aligned Ni micro-channels is designed to support the TiO2 active material. Electrochemical characterization revealed that such electrode has promising performance referring to enhanced capacity, reliable rate compatibility, and durable cyclic stability. The maximum insertion coefficient for the Li ion intercalation reaction is determined as ~0.85, which is one of the highest values for anatase anode of LIBs. Meanwhile, cross-sectional electron microscopic imaging along with X-ray energy dispersive spectroscopic elemental analysis validated the uniform spatial distribution of TiO2 nanoparticles inside the Ni micro-channels throughout cycling. Synergistic effect between nano-TiO2 active material and porous Cu/Ni current collector is the main cause. The favorable properties of the Cu/Ni/TiO2 anode are improved electrochemical reactivity, reduced lithium ion diffusion pathways, great specific surface area, effective buffering of volume changes of TiO2 nanoparticles, and the optimal paths for chargers transport.