Anion-controlled synthesis of TiO2 nano-aggregates for Li ion battery electrodes
Introduction
Titanium dioxide (TiO2) has been studied in a wide range of applications, such as solar cells [1], photocatalysts [2], gas sensors [3] and energy-storage devices [4], [5], due to its low cost, high stability, general abundance, and non-toxicity [6]. In the case of bulk TiO2, generally, the maximum insertion number of Li into TiO2 is 0.5 (Li0.5TiO2); thus, the theoretical capacity is 168 mAh g− 1. However, TiO2 particles for which the particle size is in the nano-regime (below 100 nm) change the electrochemical reactivity toward Li, increasing the electrode/electrolyte contact area and shortening the path distance for both electron and ion transport. This induces more than 0.5 Li insertion into TiO2 [7], [8], [9], [10]. Some interesting approaches for TiO2-based nano-structure materials such as nano-rods [11] and nano-tubes [12], [13], [14], which insert more than 0.5 Li as well, have been devised to operate Li-ion batteries (LIBs) at high power and high energy levels. Therefore, nano-structured and nano-sized TiO2 is regarded as an alternative to carbon-based anode materials in LIBs [15], [16].
Meanwhile, other reports have attempted to synthesize spherical TiO2 using Ti(SO4)2 [17], [18]. Among them, Wei et al. reported the synthesis of spherical anatase TiO2 powder by a hydrolysis method using a Ti(SO4)2 source [19], but the TiO2 particle size did not change below 100 nm, and the particle size was irregular. In our previous research, we synthesized nano-sized and size-tunable spherical aluminum hydrous oxide using a hydrolysis method by controlling the anion ratios without a surfactant [20].
However this hydrolysis synthesis of size-tunable, nano-sized TiO2 has rarely been addressed compared to other common oxides. In this paper, various controlled sizes of anatase TiO2 nano-aggregates (NAs) are successfully synthesized by changing the ratio of chloride and sulfate anions using a hydrolysis method at a low temperature (80 °C). The overall synthetic procedure of the TiO2 NAs is illustrated in Scheme 1. When synthesized, additives such as a template or a surfactant were not used. Furthermore, the electrochemical performances of anatase TiO2 NAs below 100 nm in size were evaluated for the application to LIB electrodes. The anatase TiO2 NAs calcined at 400 °C exhibited enhanced Li reversible storage capacities.
Section snippets
Material Synthesis
Nano-sized anatase TiO2 was synthesized by a hydrolysis method. TiCl4 (JUNSEI) and Ti(SO4)2·nH2O (extra-pure, JUNSEI) were dissolved in a 100 ml of cold deionized water. To synthesize the size-tunable anatase TiO2 NAs, the total concentration of Ti4 + was fixed at 0.001 mol and the ratio of the TiCl4 and Ti(SO4)·nH2O was changed (hereafter Cl−/SO42 −:R). After aging in a refrigerator for 2 h, the solution was reacted in an oil bath at 80 °C for 30 min. After the reaction, the obtained product was
Synthesis of Size-Tunable Anatase TiO2 NAs
Regarding the preparation of various sizes of TiO2 NAs, the anion ratios are listed in Table 1. Fig. 1 shows SEM and TEM images of TiO2 NAs with various reaction conditions. Although some particles show a tendency to grow while adhering originally to each other, i.e., not necking, due to the high hydrolysis rate of TiO2, each particle has a relatively uniform and spherical shape. More importantly, the particle size of the spherical TiO2 NAs was reduced as the ratio of chloride anions was
Conclusions
In summary, we synthesized facile, additive-free and size-controllable anatase TiO2 NAs between 150 nm and 20 nm in size by changing the ratio of the anion concentration. As the concentration of chloride ions was increased, the size of the TiO2 NAs was reduced, with each NA consisting of an aggregation of tiny primary crystallites whose sizes were about 5 nm, which resulted in a large specific surface area.
The electrochemical performances of the TiO2 NAs as an anode material for LIBs were also
Acknowledgments
This work was supported by the Global Frontier R&D Program on Center for Multiscale Energy System funded by the National Research Foundation under the Korean Ministry of Education, Science and Technology (2013-052268), and the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT and Future Planning (2012R1A2A2A01045382 and 2010-0029027). The characterization of the materials was supported by the Research Institute of Advanced Materials (RIAM).
References (47)
- et al.
Electrochemistry of anatase titanium dioxide in lithium nonaqueous cells
J. Power Sources
(1985) - et al.
Nanostructures and lithium electrochemical reactivity of lithium titanites and titanium oxides: a review
J. Power Sources
(2009) - et al.
Electrochemical properties of anatase TiO2 nanotubes as an anode material for lithium-ion batteries
Electrochim. Acta
(2007) - et al.
Preparation and mechanism of formation of titanium dioxide hydrosols of narrow size distribution
J. Colloid Interface Sci.
(1977) - et al.
Preparation of monodispersed spherical TiO2 powder by forced hydrolysis of Ti(SO4)2 solution
Mater. Lett.
(1999) - et al.
Ferric hydrous oxide sols
J. Colloid Interface Sci.
(1978) - et al.
Preparation and properties of monodispersed spherical colloidal particles of cadmium sulfide
J. Colloid Interface Sci.
(1982) - et al.
Growth mechanisms of iron oxide particles of differing morphologies from the forced hydrolysis of ferric chloride solutions
J. Colloid Interface Sci.
(1993) - et al.
Mechanism of formation of monodispersed colloids by aggregation of nanosize precursors
J. Colloid Interface Sci.
(1999) - et al.
Fabrication of rutile rod-like particle by hydrothermal method: an insight into HNO3 peptization
J. Colloid Interface Sci.
(2005)
Tailoring high-surface-area nanocrystalline TiO2 polymorphs for high-power Li ion battery electrodes
Electrochim. Acta
Nanocrystalline TiO2 (anatase) for Li-ion batteries
J. Power Sources
Lithium insertion into self-organized mesoscopic TiO2 (anatase) electrodes
Solid State Ionics
Preparation and electrochemical properties of Ag-modified TiO2 nanotube anode material for lithium-ion battery
Electrochem. Commun.
A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films
Nature
Environmental applications of semiconductor photocatalysis
Chem. Rev.
Room-temperature low-power hydrogen sensor based on a single tin dioxide nanobelt
Appl. Phys. Lett.
Rocking chair lithium battery based on nanocrystalline TiO2 (anatase)
J. Electrochem. Soc.
Issues and challenges facing rechargeable lithium batteries
Nature
Nanoionics: ion transport and electrochemical storage in confined systems
Nat. Mater.
Nanostructured materials for advanced energy conversion and storage devices
Nat. Mater.
Oriented nanostructures for energy conversion and storage
ChemSusChem
Rate characteristics of anatase TiO2 nanotubes and nanorods for lithium battery anode materials at room temperature
J. Electrochem. Soc.
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