Synthesis of One-Dimensional Mesoporous Ag Nanoparticles-Modified TiO2 Nanofibers by Electrospinning for Lithium Ion Batteries

Abstract

TiO2 is regarded as a prospective electrode material owing to its excellent electrochemical properties such as the excellent cycling stability and the high safety. However, its low capacity and low electronic conductivity greatly restrict the further improvement in electrochemical performance. A new strategy was put forward to solve the above defects involved in TiO2 in which the low capacity was enhanced by nanomerization and porosity of TiO2, and the low electronic conductivity was improved by introducing Ag with a high conductivity. One-dimensional mesoporous Ag nanoparticles-embedded TiO2 nanofibers (Ag@TiO2 nanofibers) were successfully synthesized via a one-step electrospinning process combined with subsequent annealing treatment in this study. The microstructure and morphology of mesoporous TiO2@Ag nanofibers were confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption. TiO2 nanofibers mainly consisted of a large amount of anatase TiO2, accompanied with traces of rutile TiO2. Ag nanoparticles were uniformly distributed throughout TiO2 nanofibers and promoted the transformation of TiO2 from the anatase to the rutile. The corresponding electrochemical performances are measured by galvanostatic charge-discharge, cycle stability, rate performance, cycle voltammetry, and electrochemical impedance spectroscopy measurements in this research, with pristine TiO2 nanofibers as the reference. The results indicated that the introduction of Ag nanoparticles into TiO2 nanofibers significantly improved the diffusion coefficient of Li ions (5.42 × 10−9 cm2⋅s−1 for pristine TiO2, 1.96 × 10−8 cm2⋅s−1 for Ag@TiO2), and the electronic conductivity of TiO2 (1.69 × 10−5 S⋅cm−1 for pristine TiO2, and 1.99 × 10−5 S⋅cm−1 for Ag@TiO2), based on which the comprehensive electrochemical performance were greatly enhanced. The coulombic efficiency of the Ag@TiO2 nanofibers electrode at the first three cycles was about 56%, 93%, and 96%, which was higher than that without Ag (48%, 66%, and 79%). The Ag@TiO2 nanofibers electrode exhibited a higher specific discharge capacity of about 128.23 mAh⋅g−1 when compared with that without Ag (72.76 mAh·g−1) after 100 cycles at 100 mA·g−1. With the current density sharply increased from 40 mA·g−1 to 1000 mA·g−1, the higher average discharge capacity of 56.35 mAh·g−1 was remained in the electrode with Ag, when compared with the electrode without Ag (average discharge capacity of about 12.14 mAh·g−1). When the current density was returned to 40 mA·g−1, 80.36% of the initial value was returned (about 162.25 mAh·g−1) in the electrode with Ag, which was evidently superior to that without Ag (about 86.50 mAh·g−1, only 55.42% of the initial value). One-dimensional mesoporous Ag@TiO2 nanofibers can be regarded as a potential and promising candidate as anode materials for lithium ion batteries.

Investigation of Lithium Ion Diffusion of Graphite Anode by the Galvanostatic Intermittent Titration Technique

“…The performance of LIBs is determined by lithium-ion diffusion in both the anode and cathode, which is furthermore coupled to electron transport [3]. For the practical use of electrodes, the lithium-ion diffusion coefficient of an electrode can be used as a performance descriptor [4][5][6][7].…”

Effect of Ni Doping Content on Phase Transition and Electrochemical Performance of TiO2 Nanofibers Prepared by Electrospinning Applied for Lithium-Ion Battery Anodes

“…The applied tube current and voltage were 40 mA and 40 kV. An X-ray photoelectron spectroscope detected the elements that were involved in the samples and their chemical valence states (XPS, ESCALAB 250XI, Thermo Fisher Scientific, Waltham, MA, USA), and all of the spectra were calibrated by using C 1s adventitious carbon as a reference binding energy (284.8 eV) [34]. Raman scattering was measured using a laser Raman spectrometer (Raman, inVia Reflex/inVia Reflex) with a 633 nm excitation.…”

“…In addition to nanomerization, the inclusion of additional substances, such as α-Fe 2 O 3 [29], Ag [30], graphene [31], amorphous carbon [32], and Co 3 O 4 [33], were introduced into the TiO 2 structure was also found to be an effective method for improving the electrochemical performance. Zhang et al [34] applied the electrospinning technology to prepare one-dimensional mesoporous Ag@TiO 2 nanofibers. After 100 cycles at a current density of 100 mA•g −1 , as compared to pristine TiO 2 nanofibers (73 mAh•g −1 ), mesoporous Ag@TiO 2 nanofibers had excellent discharge specific capacity of 128 mAh•g −1 .…”

Mesoporous Silica Hybridized With Gadolinium(III) Nanoplatform for Targeted Magnetic Imaging–Guided Photothermal Breast Cancer Therapy

“…As shown in Figure 2A and B, the NPs have a medium size of *113 nm and consists of an irregular, radially oriented mesostructured, which is further confirmed by the TEM microscopy. [24][25][26] Continuous radial mesostructure suggests that this kind of mesoporous Gd-MSN-NPs can allow guest nanoparticles or molecules, such as anticancer therapies, to be loaded or adsorbed and published. Eventually, Gd-MSN@Bt-NPs and Gd-MSN@uFe-Bt-NPs were synthesized by modifying the surfaces with biotin and using a cross-linker to load uFe-NPs in the radial mesonanostructure of Gd-MSN-NPs.…”