Titanium Monoxide with in Situ Grown Rutile TiO2Nanothorns as a Heterostructured Job-Sharing Anode Material for Lithium-Ion Storage

Abstract

Developing high-performance anodes is highly desired to meet the recent ever-increasing demands for high-energy lithium-ion batteries (LIBs). Titanium dioxide (TiO2) shows extremely stable performance as an anode material in LIBs, but its intrinsic structural limit critically inhibits the full utilization of the TiO2 material. Herein, we report a uniquely integrated heterostructure of rutile TiO2 (r-TiO2) nanothorns grown in situ over a new porous and conductive cubic crystalline titanium monoxide (TiO) core. The new cubic crystalline TiO is prepared from phase transformation of anatase TiO2 by pyrolysis with Mg metal at 650 °C, and subsequent oxidative HCl treatment enables in situ growth of r-TiO2 nanothorns on the surface of the porous TiO. Interestingly, the mixed-phased novel hybrid as an anode exhibits a new Li-ion charging mechanism consisting of two independent reactions of intercalation and pseudocapacitive interaction corresponding to the two different phases of r-TiO2 and TiO, respectively, in the composite for Li-ion storage. Thus, it illustrates high reversible capacity and almost no capacity decay during 1000 cycles at a high current density of 20 C (4000 mA g-1), overcoming the issues of conventional TiO2. In particular, the excellent rate capability along with a long cycle life enables the new hybrid to have ultrafast charging of the system. Furthermore, unlike a conventional TiO2 anode working in the potential range (1.0-3.0 V), the hybrid with the job-sharing property exhibits stable charge-discharge performance over a wider potential window range of 0.01-3.0 V, particularly even in the low potential range of 0.01-1.0 V. All the properties including the wider potential window allow the hybrid to realize the highest electrochemical performance that titanium oxides have ever achieved so far. © 2022 American Chemical Society.