A Porous TiO₂Electrode Prepared by an Energy Efficient Pyro-Synthesis for Advanced Lithium-Ion Batteries

Abstract

Anatase-type titanium dioxide (TiO 2 ) anodes were prepared by a polyol-assisted pyro-synthetic process followed by mild annealing at temperatures in the range of 300 to 600 • C for 3 h. The XRD studies clearly revealed the formation of anatase-type TiO 2 for all of the prepared samples. The average crystallite size, calculated using the Scherrer formula, was determined to be less than 50 nm in all samples. Electron microscopy studies revealed that the particle-size in all samples ranged from 5 to 50 nm. N 2 adsorption studies confirmed that the samples show mesoporous characteristics and in particular the TiO 2 anode prepared at 500 • C demonstrated a unique tri-porous feature that appears to benefit its electrochemical performances vs. lithium. Although there is no order of variation in the particle-size of the samples prepared at temperatures under 600 • C, the tri-porous feature in combination with the sufficiently high particle crystallinity in the TiO 2 anode prepared at 500 • C appears to contribute to its impressive electrochemical lithium storage properties among the prepared electrodes. The pyro-synthetic strategy aids in developing nanostructured battery electrodes with porous morphologies and appears to offer promise for being developed as an energy saving process for large-scale applications. Rechargeable Li-ion batteries (LIBs) are state-of-the-art devices in the field of electrochemical energy storage due to their high energy densities and extensive usage for a wide range of applications, including portable electronics, electric vehicles, stationary storage, and medical devices.1-5 However, their short cycle-life and safety issues due to rapid charging, charging at low temperatures, and lithium plating on graphite remain as obstacles to the realization of next generation LIBs. 6,7 In particular, the use of graphite anodes limits the performance and increases the safety risks of the current LIBs. Since their electrochemical properties and safety issues are critically dependent on the electrode materials, much effort has been made to develop alternative anodes based on transition metal oxides in an attempt to produce safer LIBs exhibiting higher performance. [8][9][10][11][12][13][14][15][16][17][18] In this regard, anatase-type TiO 2 anodes with a relatively high voltage potential (∼1.7 V) vs. Li/Li + , high capability, thermodynamic stability, low safety risks, and costs have been widely investigated.15-21 Despite these advantages, the low electronic conductivity and lithium diffusivity within the lattice restricts the application of TiO 2 as a high-power anode.22-24 For instance, the theoretical specific capacity of TiO 2 is high (335 mAh g −1 ); however, in reality, only 0.5 mol lithium (equivalent to a specific capacity of 168 mAh g −1 ) is reversibly inserted per formula unit of TiO 2 consisting of micro-sized particles. The established strategy to overcome this drawback is to develop composite/coating with metals (Cu, Sn, Ag, Au), metal oxides (SnO, SnO 2 , RuO 2 ) and carbonaceous materials ...

One‐Step Pyro‐Synthesis of a Nanostructured Mn3O4/C Electrode with Long Cycle Stability for Rechargeable Lithium‐Ion Batteries

“…The estimated inter‐planar spacing values of 0.48 and 0.28 nm corresponding to the (110) and (200) planes of Mn 3 O 4 (JCPDS 89‐4837), respectively, which are well‐matched with the XRD peaks (Figure ), are also displayed in Figure c. In addition, the highly magnified image reveals the presence of an amorphous carbon layer of thickness 2–3 nm along the boundaries of the primary Mn 3 O 4 nanoparticles. In fact, our earlier studies on battery electrode synthesis utilizing the pyro‐reaction revealed that the hydrocarbon‐based polyol can act as a carbon source during the polyol combustion and thereby contribute to the formation of carbon in the as‐prepared powders . The selected area electron diffraction (SAED) pattern, in Figure d, depicts faint rings with bright spots that are characteristic of crystalline nanomaterials.…”

“…In fact, our earlier studies on batterye lectrode synthesis utilizingt he pyro-reactionr evealed that the hydrocarbonbased polyol can act as ac arbon source during the polyol combustion and therebyc ontributetot he formation of carbon in the as-prepared powders. [32,33] The selected area electron diffraction (SAED) pattern, in Figure 2d Figure 2d.W ith the aim of understanding the amount of carbon, elemental analysisw as performed and the results indicate the presence of 13 %c arbon content in the asprepared sample. This carbon contenta ppears to be sufficient for the formation of ac arbon-coating layer on the surfaceo f the particles.…”

“…It is worth notingt hat the presentsynthesis provides ac ost-effective and simple strategy to produce carbon-coated nanoparticles. [29][30][31][32][33] Figure 4s hows the N 2 adsorption-desorption isotherm and the Barrett-Joyner-Halenda (BJH) pore-size distribution of the nanostructured Mn 3 O 4 /C. Ad istinct hysteresis in the larger range around 0.7 to 1.0 P/P o suggestst he formation of meso/ macropores that most likely originatesf rom the spaces within the aggregated particles.…”

“…To initiate the combustion process, an electric torch was used and rapid precipitation of nanoparticles occurred. [29][30][31][32][33] The entire process is completed in af ew seconds. The as-prepared specimen obtained directly after the combustion was then thoroughly ground and used as the final product for characterization without any further heat treatment.…”

Enabling Green Fabrication of Li-Ion Battery Electrodes by Electrophoretic Deposition: Growth of Thick Binder-Free Mesoporous TiO2-Carbon Anode Films

“…21 A lot of this research has focused on nano-TiO 2 of different polymorphs, such as anatase, rutile, or brookite of different nanostructures and their Li-ion storage properties and performance. 11,[22][23][24][25][26][27][28] In the present work as the focus is the electrophoretic deposition method we opted to use commercial TiO 2 nanomaterial P25 (commonly used as photocatalyst) as the active anode component. 29 Both standard PVDF binder-based (STD) and EPD-built P25 TiO 2 -carbon films on aluminum substrate are prepared, characterized, and electrochemically analyzed revealing in a headto-head comparison the great inherent potential of electrophoretic deposition in fabricating superior structure Li-ion battery electrodes.…”