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would impose restrictions on the penetration of LIBs into these large-volume markets. [3,4] In addition, after 25 years of continuous improvements, the mature LIBs technology is approaching a fundamental limit in terms of energy density (slightly above 300 W h kg −1 ) and costs at the materials level. [4][5][6] With the aforementioned concerns, alternative battery concepts have significantly stimulated research interests to further drive battery technologies to increase both the gravimetric and volumetric energy densities, reduce the cost, and expand the cycling life. [3,6,7] The "beyond Li-ion" technologies such as lithium-air, lithium-sulfur (Li-S), multivalent batteries, and solid-state batteries show the unique feature of using metal anodes that can store more energy via a reversible metal plating/stripping process. Unfortunately, these emerging or reviving technologies involving lithium metal inevitably meet the critical challenges of resource shortage. Furthermore, the high reactivity of lithium metal leads to electrolyte consumption and nonuniform lithium distribution (even dendritic growth) during cycling. These issues still hamper the mainstream commercialization of the lithium-metal-based batteries. [8,9] Rechargeable magnesium (Mg) batteries may offer considerable advantages (see Table 1) over Li-metal batteries because the metallic Mg anode shows double the volumetric capacity, safer and easier processing features, more uniform and nondendritic electroplating during cell charging, and cheaper costs due to its greater abundance in the earth crust. [4,[10][11][12][13] Based on these advantages, intensive attention has been garnered toward the development of new electrolytes, cathodes, and their corresponding mechanistic understandings for the rechargeable Mg batteries. Additionally, several industries including Pellion Technologies (a spin-off company from Massachusetts Institute of Technology), the Toyota Research Institute of North America, and recently Sony Corporation have initiated R&D projects for the rechargeable Mg batteries and tried to find practical application pathways. Nonetheless, developing a high-energy-density Mg battery with long cycle life and high rate capability is still a huge challenge due to the lack of high-performance cathodes and suitable Mg-ion electrolytes. [9,12] It is fair to state that the Chevrel phases, reported by Aurbach et al. in 2000, are still the most attractive Mg-ion Rechargeable magnesium (Mg) batteries are one of the potential contenders to replace current Li-ion batteries to power future electric vehicles with lower cost, higher safety, and extended mileage. To achieve this goal, both high-voltage intercalation-type cathodes and high-capacity conversion-type cathodes are considered. However, there are still no reports to compare rechargeable Mg batteries with the state-of-the art Li-ion batteries in terms of their overall performance. Also, potential cathode materials to deliver higher energy density in rechargeable Mg batteries are rarely summarized. Here, t...

Orthorhombic V(2)O(5) single-crystalline nanobelts with widths of 100-300 nm, thicknesses of 30-40 nm, and lengths up to tens of micrometers have been synthesized on a large scale in a hydrogen peroxide aqueous solution by an environmentally friendly chemical route. Such nanobelts grow along the direction of [010]. The influence of the reaction time on the crystal structures and morphologies of the resulting products are investigated. A probable dehydration-recrystallization-cleavage mechanism for the formation of V(2)O(5) nanobelts is proposed. The experiments demonstrate that the use of a nanosized belt-like structure can considerably enhance the specific discharge capacity in lithium-ion batteries.

Building heterostructures containing dissimilar coupling components with different bandgaps can promote interfacial reaction kinetics and accelerate charge carrier transport for Li–S batteries.

MoO(3) nanostructures with different morphologies, such as helical nanosheets, crosslike nanoflowers, and nanobelts, have been synthesized on a large scale by an environmentally friendly chemical route. The evolution process from helical nanosheets to crosslike nanoflowers to nanobelts is observed for the first time. The influences of reaction time and the molar ratio of molybdenum and H(2)O(2) on the morphologies of MoO(3) nanostructures have been investigated. The synthetic process is environmentally friendly and may be extended to synthesize nanostructures of other metal (W, Ti, and Cr) oxides.