Concept: Electric car
We demonstrate a simple, efficient, yet versatile strategy for the synthesis of novel hierarchical heterostructures composed of TiO(2) nanofiber stem and various metal oxides (MOs) secondary nanostructures, including Co(3)O(4), Fe(2)O(3), Fe(3)O(4), and CuO, by advantageously combining the versatility of the electrospinning technique and hydrothermal growth method, for which the controllable formation process and possible formation mechanism are also investigated. Moreover, as a proof-of-concept demonstration of the functional properties of these hierarchical heterostructures, the Co(3)O(4)/TiO(2) hierarchical heterostructures are investigated as the lithium-ion batteries (LIBs) anode materials for the first time, which not only delivers a high reversible capacity of 632.5 mAh g(-1) and 95.3% capacity retention over 480 cycles, but also shows excellent rate capability with respect to the pristine TiO(2) nanofibers. The synergetic effect between Co(3)O(4) and TiO(2) as well as the unique feature of hierarchical heterostructures are probably responsible for the enhanced electrochemical performance.
The omnipresence of lithium-ion batteries in mobile electronics, and hybrid and electric vehicles necessitates discovery of new lithium resources to meet rising demand and to diversify the global lithium supply chain. Here we demonstrate that lake sediments preserved within intracontinental rhyolitic calderas formed on eruption and weathering of lithium-enriched magmas have the potential to host large lithium clay deposits. We compare lithium concentrations of magmas formed in a variety of tectonic settings using in situ trace-element measurements of quartz-hosted melt inclusions to demonstrate that moderate to extreme lithium enrichment occurs in magmas that incorporate felsic continental crust. Cenozoic calderas in western North America and in other intracontinental settings that generated such magmas are promising new targets for lithium exploration because lithium leached from the eruptive products by meteoric and hydrothermal fluids becomes concentrated in clays within caldera lake sediments to potentially economically extractable levels.Lithium is increasingly being utilized for modern technology in the form of lithium-ion batteries. Here, using in situ measurements of quartz-hosted melt inclusions, the authors demonstrate that preserved lake sediments within rhyolitic calderas have the potential to host large lithium-rich clay deposits.
Silicon is produced in a variety of ways as an ultra-high capacity lithium-ion battery (LIB) anode material. The traditional carbothermic reduction process required is expensive and energy-intensive; in this work, we use an efficient magnesiothermic reduction to convert the silica-based frustules within diatomaceous earth (diatomite, DE) to nanosilicon (nanoSi) for use as LIB anodes. Polyacrylic acid (PAA) was used as a binder for the DE-based nanoSi anodes for the first time, being attributed for the high silicon utilization under high current densities (up to 4C). The resulting nanoSi exhibited a high BET specific surface area of 162.6 cm(2) g(-1), compared to a value of 7.3 cm(2) g(-1) for the original DE. DE contains SiO2 architectures that make ideal bio-derived templates for nanoscaled silicon. The DE-based nanoSi anodes exhibit good cyclability, with a specific discharge capacity of 1102.1 mAh g(-1) after 50 cycles at a C-rate of C/5 (0.7 A gSi(-1)) and high areal loading (2 mg cm(-2)). This work also demonstrates the fist rate capability testing for a DE-based Si anode; C-rates of C/30 - 4C were tested. At 4C (14.3 A gSi(-1)), the anode maintained a specific capacity of 654.3 mAh g(-1) - nearly 2x higher than graphite’s theoretical value (372 mAh g(-1)).
Porous SnO(2)/graphene composite thin films are prepared as anodes for lithium ion batteries by the electrostatic spray deposition technique. Reticular-structured SnO(2) is formed on both the nickel foam substrate and the surface of graphene sheets according to the scanning electron microscopy (SEM) results. Such an assembly mode of graphene and SnO(2) is highly beneficial to the electrochemical performance improvement by increasing the electrical conductivity and releasing the volume change of the anode. The novel engineered anode possesses 2134.3 mA h g(-1) of initial discharge capacity and good capacity retention of 551.0 mA h g(-1) up to the 100th cycle at a current density of 200 mA g(-1). This anode also exhibits excellent rate capability, with a reversible capacity of 507.7 mA h g(-1) after 100 cycles at a current density of 800 mA g(-1). The results demonstrate that such a film-type hybrid anode shows great potential for application in high-energy lithium-ion batteries.
A rapid and controllable route is developed for the synthesis of MnO nanoparticles that are encapsulated uniformly in three-dimensional (3D) mesoporous interconnected carbon networks (MnO-MICN) through an efficient microwave-polyol process combined with a subsequent thermal treatment. The dependence of sodium citrate on the morphology of the Mn-based precursors was investigated systematically. Results show that the unique mesoporous interconnected carbon network (MICN) can not only buffer the large volume expansion of MnO during the electrochemical cycling, but also improve the electrode/electrolyte contact area, favoring the fast Li-ion transport and high specific capacity, superior cyclability, and excellent rate capability. When evaluated as an anode material for lithium-ion batteries, the as-formed 3D MnO-MICN nanocomposite exhibits a highly reversible capacity of 1224 mAh g-1 with a Coulombic efficiency of ~99% at a current density of 200 mA g-1 over 200 cycles.
Binary transition metal oxides have been attracting extensive attention as promising anode materials for lithium-ion batteries, due to their high theoretical specific capacity, superior rate performance and good cycling stability. Here, loaf-like ZnMn(2)O(4) nanorods with diameters of 80-150 nm and lengths of several micrometers are successfully synthesized by annealing MnOOH nanorods and Zn(OH)(2) powders at 700 °C for 2 h. The electrochemical properties of the loaf-like ZnMn(2)O(4) nanorods as an anode material are investigated in terms of their reversible capacity, and cycling performance for lithium ion batteries. The loaf-like ZnMn(2)O(4) nanorods exhibit a reversible capacity of 517 mA h g(-1) at a current density of 500 mA g(-1) after 100 cycles. The reversible capacity of the nanorods still could be kept at 457 mA h g(-1) even at 1000 mA g(-1). The improved electrochemical performance can be ascribed to the one-dimensional shape and the porous structure of the loaf-like ZnMn(2)O(4) nanorods, which offers the electrode convenient electron transport pathways and sufficient void spaces to tolerate the volume change during the Li(+) intercalation. These results suggest the promising potential of the loaf-like ZnMn(2)O(4) nanorods in lithium-ion batteries.
Hollow 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) microspheres are synthesized on a large scale through a simple in situ template-sacrificial route. Starting from porous MnO(2) microspheres, the hollow microspheres assembled with 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) nanocrystals are formed by a nanoscale Kirkendall effect. The nanocrystal-assembled hollow 0.3Li(2)MnO(3)·0.7LiNi(0.5)Mn(0.5)O(2) microspheres exhibit a highly reversible capacity as high as 295 mAh g(-1) over 100 cycles and excellent rate capability (125 mAh g(-1) at 1000 mA g(-1)). Benefitting from a unique hollow and nanocrystalline architecture, the as-formed hollow microspheres show much enhanced high-temperature (55 °C) electrochemical performances, compared with the products obtained by conventional sol-gel/solid-state reaction methods. This work demonstrates that a fabrication strategy based on the present in situ template-sacrificial approach offers a new method for the design of high-performance cathode materials with hollow interiors for Li-ion battery applications.
We report a facile ‘one-pot’ method for the synthesis of Sn embedded carbon-silica (CS) mesostructured (nanostructured) composites through the selective interaction of resol (carbon precursor), tetraethylorthosilicate (TEOS), and tributylphenyltin (Sn precursor) with an amphiphilic diblock copolymer, poly (ethylene oxide-b-styrene), PEO-b-PS. A unique morphology transition from Sn nanowires to spherical Sn nanoparticles embedded in CS framework has been obtained. Metallic Sn species are homogeneously embedded in a rigid CS framework and are effectively confined within the nanostructures. The resulting composites are used as anode materials for lithium-ion batteries and exhibit high specific capacities (600 mA h g -1 at a current density of 45 mA g-1, 440 mA h g-1 at a current density of 300 mA g-1) and an excellent cyclability of over 100 cycles with high coulombic efficiency. Most of all, the novel method developed in this work for synthesizing functional hybrid materials can be extended to the preparation of various functional nanocomposites owing to its versatility and facileness.
A facile, environmentally friendly, and economical synthetic route for production of large-amounts (gram scale) of two-dimensional (2D) layered SnS(2) nanoplates is presented. The electrode fabricated from the SnS(2) nanoplate exhibits excellent lithium-ion battery performance with highly reversible capacity, good cycling stability and excellent capacity retention after 30 cycles.
A facile process is demonstrated for the synthesis of layered SiCN-MoS2 structure via pyrolysis of polysilazane functionalized MoS2 flakes. The layered morphology and polymer to ceramic transformation on MoS2 surfaces was confirmed by use of electron microscopy and spectroscopic techniques. Tested as thick film electrode in a Li-ion battery half-cell, SiCN-MoS2 showed the classical three-stage reaction with improved cycling stability and capacity retention than neat MoS2. Contribution of conversion reaction of Li/MoS2 system on overall capacity was marginally affected by the presence of SiCN while Li-irreversibility arising from electrolyte decomposition was greatly suppressed. This is understood as one of the reasons for decreased first cycle loss and increased capacity retention. SiCN-MoS2 in the form of self-supporting paper electrode (at 6 mg·cm(-2)) exhibited even better performance, regaining initial charge capacity of approximately 530 mAh·g(-1) when the current density returned to 100 mA·g(-1) after continuous cycling at 2400 mA·g(-1) (192 mAh·g(-1)). MoS2 cycled electrode showed mud-cracks and film delamination whereas SiCN-MoS2 electrodes were intact and covered with a uniform solid electrolyte interphase coating. Taken together, our results suggest that molecular level interfacing with precursor-derived SiCN is an effective strategy for suppressing the metal-sulfide/electrolyte degradation reaction at low discharge potentials.