RGO-Coated TiO₂ Microcones for High-Rate Lithium-Ion Batteries

Abstract

Reduced graphene oxide (RGO)-coated TiO 2 microcones have been synthesized via simple anodization and cyclic voltammetry for use in lithium-ion batteries (LIBs). Microcones had a perpendicularly oriented hollow core, an anatase structure, and a high surface area, allowing higher capacity than other nanosized TiO 2 structures. TiO 2 has low electrical conductivity, leading to the limitation of fast charging and high capacity; however, this was improved by the application of an RGO coating in this work. As anode materials of LIB, the obtained RGO microcone showed a capacity of 157 mAh g –1 at 10C (fully charged within ∼360 s) and sustained 1000 cycles with only 0.02% capacity fading per cycle. The capacity was 1.5 times higher than that of conventional microcone. We speculated that the decrease in the charge-transfer resistance ( R ct ) played a crucial role in increasing the capacity with fast charging.

Pan‐Milling: Instituting an All‐Solid‐State Technique for Mechanical Metastable Oxides as High‐Performance Lithium‐Ion Battery Anodes

“…These results indicate that the pan‐milled uniform TiO 2 nanoparticles@graphene structure is beneficial to enhancing the ionic conductivity of the composite electrodes. Furthermore, in comparison with other TiO 2 /graphene composite electrodes with different morphologies and structures prepared by chemical methods reported in literature, 61–70 ] as shown in Figure 5g and Table S3 (Supporting Information), our pan‐milled sample is among the top set in terms of specific capacity. Considering it as a simple all‐solid‐state technique without laborious morphology or structure modification, pan‐milling mechanochemistry puts in great potential for preparation of high‐performance nanocomposite electrode materials, especially metastable oxides.…”

“…a) Cyclic voltammograms (CVs) of the pan‐milled TiO 2 /GNS‐P‐20 in the voltage range of 1–3 V (vs Li/Li + ) at a scan rate of 0.2 mV s –1 , b) first cycle galvanostatic charge–discharge profiles, and c) cycling performances of the pristine TiO 2 , ball‐milled and pan‐milled TiO 2 /GNS composite electrodes cycled at a specific current density of 100 mA g –1 between 1 and 3 V (vs Li/Li + ), d) rate performances of pristine TiO 2 and TiO 2 /GNS‐P‐20, e) long‐term cycling performances of the pristine TiO 2 and the pan‐milled TiO 2 /GNS‐P‐20 at a specific current density of 1 A g –1 between 1 and 3 V (vs Li/Li + ), f) Nyquist plots before and after cycling for 100 cycles with the fitted curves (inset is the equivalent circuit used to fit the experimental data) of the pristine TiO 2 and the pan‐milled TiO 2 /GNS‐P‐20, and g) comparison of gravimetric specific capacity of TiO 2 ‐GNS‐P‐20 in this work with other typical TiO 2 ‐GNS electrodes reported in literature (the white numbers in the histogram represent the current density). [ 61–70 ] …”

Microwave-Assisted Rapid Synthesis of Eu(OH)3/RGO Nanocomposites and Enhancement of Their Antibacterial Activity against Escherichia coli

“…Two major peaks corresponding to the D band and G band were observed at 1350 and 1580 cm −1 , respectively. The D band corresponded to the local defects and disorder of the graphite layers, whereas the G band, which is related to the sp 2 hybridized structure [ 46 ], corresponded to the crystallizability and symmetry of the graphitic carbonaceous materials [ 47 ]. In addition, three Raman peaks were observed at 300.9, 376.1, and 485.4 cm −1 in the Raman spectra of Eu(OH) 3 with a hexagonal crystal phase (P63/m), which could be attributed to A g translatory, E 2g translatory, and E 1g libration modes, respectively ( Figure 3 ) [ 20 ].…”

Nanostructured Graphene Oxide-Based Hybrids as Anodes for Lithium-Ion Batteries

“…The reversible lithium-storage capacity reached 161 mAh g −1 after 50 cycles with~70% retention at a current rate of 170 mA g −1 (0.5C). Park et al have synthesized rGO-coated TiO 2 microcones as composite anode materials via simple anodization and cyclic voltammetry [351]. The obtained TiO 2 /rGO hybrid showed a capacity of 157 mAh g −1 at 10C rate and sustained 1000 cycles with only 0.02% capacity fading per cycle.…”