Titanium Monoxide with in Situ Grown Rutile TiO₂ Nanothorns 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.

Magnesium: properties and rich chemistry for new material synthesis and energy applications

“…successfully prepared the surface-defected TiO 2− x with surface oxygen deficiency through calcination at the melting point of Mg (650 °C) by varying the mole ratio of the anatase TiO 2 and Mg (RT- y , where RT indicates reduced TiO 2 and y is the mole ratio of Mg to TiO 2 ). 33 Key observations here showed that when the mole ratio was below the threshold value of 0.75 mole ratio, Mg only reacted at the surface of TiO 2 to generate a superficial TiO 2− x and MgO, leaving behind a core of unreacted TiO 2 (TiO 2 @TiO 2− x –MgO). The reaction follows; TiO 2 + Mg → TiO 2− x + x MgO (0 < x < 1).…”

“…In addition to high surface area, porosity provides important deposition sites for active metals and mass transfer channels which are highly necessary for catalysis. 33 Highly porous and shape-dependent materials have been successfully prepared for numerous energy applications by employing hard templates such as zeolites, 46 mesoporous silicas, 47 and some metal oxides. 48 However, the preparation processes associated with these hard templates are complicated and environmentally unfriendly, especially for the removal of silica, which requires corrosive HF or NaOH.…”

“…Some research groups have effectively employed this unique approach to create porous structures in carbon, 32 silica, 30 and metal oxides. 33 For example, in two separate reports, Sinhamahapatra et al prepared a surface-defected TiO 2Àx , from the calcination of anatase TiO 2 in the presence of Mg, while Kang et al also adopted a similar synthesis process to develop a porous cubic TiO phase. 33,34 In detail, Sinhamahapatra et.…”

Fast Li‐ion Storage and Dynamics in TiO2 Nanoparticle Clusters Probed by Smart Scanning Electrochemical Cell Microscopy

“…Li‐ion batteries are the frontrunner technology for high‐power and intermediate‐scale energy storage used in a broad range of applications, including electric vehicles and portable devices [1] . Anatase TiO 2 is a promising fast‐charging material for Li‐ion battery anodes with theoretical specific charge capacities competitive with those of graphite electrodes [2–8] . TiO 2 is abundant, inexpensive [6] and shows low volume changes (<4 %) during Li + (de)intercalation: [9] $$$\vcenter{\openup.5em\halign{$\displaystyle{#}$\cr {{\rm T}{\rm i}{\rm O}}_{2}+{x{\rm L}{\rm i}}^{+}+{x{\rm e}}^{-}{\rm \ }{\stackrel{ {\rightarrow} } { {\leftarrow} } } {\rm \ }{{\rm L}{\rm i}}_{x}{{\rm T}{\rm i}{\rm O}}_{2}\hfill\cr}}$$$ …”

Intelligente elektrochemische Rasterzellmikroskopie für den Nachweis schneller Li‐Ionen‐Speicherung und Dynamik in TiO2‐Nanopartikeln

“…Li‐Ionen‐Batterien sind die führende Technologie für die Speicherung von Energie in hohem und mittlerem Umfang, die in einem breiten Spektrum von Anwendungen einschließlich Elektrofahrzeugen und tragbaren Geräten zum Einsatz kommt [1] . Anatas‐TiO 2 ist ein vielversprechendes, schnell aufladbares Material für Li−Ionen‐Batterieanoden mit theoretischen spezifischen Ladekapazitäten, die mit denen von Graphitelektroden konkurrieren können [2–8] . TiO 2 ist reichlich vorhanden, kostengünstig [6] und zeigt geringe Volumenänderungen (<4 %) während der Li + (De)Intercalation [9] .…”