Dehydration of Alginic Acid Cryogel by TiCl₄ vapor: Direct Access to Mesoporous TiO₂@C Nanocomposites and Their Performance in Lithium‐Ion Batteries

Abstract

A new strategy for the synthesis of mesoporous TiO2@C nanocomposites through the direct mineralization of seaweed‐derived alginic acid cryogel by TiCl4 through a solid/vapor reaction pathway is presented. In this synthesis, alginic acid cryogel can have multiple roles; i) mesoporous template, ii) carbon source, and iii) oxygen source for the TiO2 precursor, TiCl4. The resulting TiO2@alginic acid composite was transformed either into pure mesoporous TiO2 by calcination or into mesoporous TiO2@C nanocomposites by pyrolysis. By comparing with a nonporous TiO2@C composite, the importance of the mesopores on the performance of electrodes for lithium‐ion batteries based on mesoporous TiO2@C composite was clearly evidenced. In addition, the carbon matrix in the mesoporous TiO2@C nanocomposite also showed electrochemical activity versus lithium ions, providing twice the capacity of pure mesoporous TiO2 or alginic acid‐derived mesoporous carbon (A600). Given the simplicity and environmental friendliness of the process, the mesoporous TiO2@C nanocomposite could satisfy the main prerequisites of green and sustainable chemistry while showing improved electrochemical performance as a negative electrode for lithium‐ion batteries.

Carbon Nanolayer-Wrapped Mesoporous TiO2–B/Anatase for Li+ Storage

“…It is observed that the fast charge transfer process conduce to the high rate performance of TiO 2 –B/anatase@C anodes. Furthermore, the diffusion which affects the rate performance of electrodes could be calculated through Warburg impedance according to the following equations. , where R , T , A , c , and F represents the gas constant, the absolute temperature, the contact area of the electrode, the concentration of Li + , and the Faraday constant, respectively, and σ is the Warburg coefficient which could be evaluated by the slope of Z ′ versus ω –1/2 in the low frequency linear region in terms of eq . The fitting results of the linear regions are shown in Figure S12, and TiO 2 –B/anatase@C-6 shows a higher D Li + (4.66 × 10 –13 cm 2 s –1 ) than that of TiO 2 –B/anatase@C-4 (7.82 × 10 –15 cm 2 s –1 ), TiO 2 –B/anatase@C-5 (1.05 × 10 –14 cm 2 s –1 ), and TiO 2 –B/anatase@C-7 (7.70 × 10 –14 cm 2 s –1 ), demonstrating a faster electrochemical kinetics for TiO 2 –B/anatase@C-6.…”

“…The effective approaches include introducing a dual even polyphase to create interface or lattice mismatch, , constructing a mesoporous structure to reduce the Li + diffusion length, , and combining with carbon-based materials to strengthen the electric mobility and further alleviate the volume expansion. , These three distinct and feasible approaches are demonstrated to improve the final electrochemical performance.…”

TinO2n−1 Suboxide Phases in TiO2/C Nanocomposites Engineered by Non-hydrolytic Sol–Gel with Enhanced Electrocatalytic Properties

“…To better understand the mechanisms involved in the carbothermal reduction and to identify the key parameters, other NHSG routes, with various oxygen donors and carbon sources, should be considered to yield smaller nanocrystals and/or higher carbon contents. The use of innocuous alternatives to THF, such as polysaccharides [ 59 ], should be also investigated to make the whole procedure safer and more sustainable. Besides, alternative reduction protocols are currently considered to yield more advanced reduction reactions, such as higher temperatures, the use of hydrogen gas or the addition of oxygen scavengers.…”

Ultrasmall TiOx Nanoparticles Rich in Oxygen Vacancies Synthesized through a Simple Strategy for Ultrahigh‐Rate Lithium‐Ion Batteries

“…[6][7][8] Among them, titanium dioxide (TiO 2 ), which has polymorphs such as amorphous, [9,10] anatase, [11,12] rutile [13] and brookite, [14,15] has been intensively studied as the anode material for LIBs because of its low cost, low or non-toxicity, ability to prevent lithium plating or better safety (due to its appropriate lithium insertion potential with a plateau above 1.5 V versus Li/ Li + ), [16,17] and good structure stability (only 3-4 % volume expansion during lithium insertion). [16,18,19] However, its lithium storage performance, especially at high rates, is severely limited by its low intrinsic electrical conductivity [20,21] and poor lithium ion diffusion kinetics. [22,23] Numerous efforts have been devoted to improving the lithium storage performance of TiO 2 , which include reducing the particle size, [24,25] coating particles with conductive carbon or forming composites with carbon, [10,26,27] heteroatom doping [28][29][30] and defect engineering.…”

“…Some transition metal oxides have shown great potentials as high‐performance anodes for LIBs . Among them, titanium dioxide (TiO 2 ), which has polymorphs such as amorphous, anatase, rutile and brookite, has been intensively studied as the anode material for LIBs because of its low cost, low or non‐toxicity, ability to prevent lithium plating or better safety (due to its appropriate lithium insertion potential with a plateau above 1.5 V versus Li/Li + ), and good structure stability (only 3–4 % volume expansion during lithium insertion) . However, its lithium storage performance, especially at high rates, is severely limited by its low intrinsic electrical conductivity and poor lithium ion diffusion kinetics .…”