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Transition metal (TM) atoms bound to fullerenes are proposed as adsorbents for high density, room temperature, ambient pressure storage of hydrogen. C60 or C48B12 disperses TMs by charge transfer interactions to produce stable organometallic buckyballs (OBBs). A particular scandium OBB can bind as many as 11 hydrogen atoms per TM, ten of which are in the form of dihydrogen that can be adsorbed and desorbed reversibly. In this case, the calculated binding energy is about 0.3 eV/H(2), which is ideal for use on board vehicles. The theoretical maximum retrievable H2 storage density is approximately 9 wt %.

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Rechargeable Li-ion batteries are currently being explored for high-power applications such as electric vehicles. However, in order to deploy Li-ion batteries in next-generation vehicles, it is essential to develop electrodes made from durable, nontoxic, and inexpensive materials with a high charge/discharge rate and a high reversible capacity. Transition metal oxides such as Fe

Electrochromic (EC) materials change their optical properties (darken/lighten) in the presence of a small electric potential difference, and are suitable for application in energy-efficient windows, antiglare automobile rear-view mirrors, sunroofs, displays, and hydrogen sensors. [1][2][3][4] There are two important criteria for selecting an EC material. The first is the time constant of the ion-intercalation reaction, which is limited both by the diffusion coefficient and by the length of the diffusion path. While the former depends on the chemical structure and crystal structure of the metal oxide, the latter is determined by the material's microstructure. [11] In the case of a nanoparticle, the smallest dimension is represented by the diffusion path length. Thus, designing a nanostructure with a small radius, while maintaining the proper crystal structure, is key to obtaining a material with fast insertion kinetics, enhanced durability, and superior performance. The second important criterion is coloration efficiency (CE), the change in optical density (OD) per unit inserted charge (Q), that is, CE = D(OD)/DQ. [12] A high CE provides large optical modulation with a small charge insertion or extraction. This is a crucial parameter for EC devices, since a lower charge-insertion or -extraction rate enhances the longterm cycling stability. Among inorganic materials, tungsten oxides have been most extensively studied. Up until now, amorphous WO 3 films have exhibited the highest CE in the visible region of the electromagnetic spectrum. However, because of their high dissolution rate in acidic electrolyte solutions, these films can only be used in lithium-based electrolytes, resulting in slower response times. Furthermore, extended durability, even in Li + systems, has not yet been demonstrated. Inexpensive conducting and redox polymers have attracted increased attention for use as EC materials because of their fast response times and high contrast ratios. [13][14][15] However, disadvantages include multiple coloration in the visible spectral range and poor UV stability. By fabricating EC films from crystalline WO 3 nanoparticles, the state-of-the-art technology of producing EC materials has been profoundly advanced. Crystalline WO 3 nanoparticles have been grown by an economical hot-wire chemical-vapordeposition (HWCVD) process, and a unique electrophoresis technique is employed for the fabrication of porous nanoparticle films. The porosity of the films not only increases the surface area and ion-insertion kinetics, but also reduces the overall material cost, leading to an inexpensive, large-area EC material. Compared to conventional amorphous WO 3 films prepared by vacuum deposition, nanoparticle films deposited by electrophoresis exhibit vastly superior electrochemical-cycling stability in acidic electrolytes, a higher charge density, and comparable CE. This greatly enhanced stability and charge capacity are attributed to the crystalline nanoparticles employed in this work. These initial results will ultimately ...

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In order to employ Li-ion batteries (LIBs) in next-generation hybrid electric and/or plug-in hybrid electric vehicles (HEVs and PHEVs), LIBs must satisfy many requirements: electrodes with long lifetimes (fabricated from inexpensive environmentally benign materials), stability over a wide temperature range, high energy density, and high rate capability. Establishing long-term durability while operating at realistic temperatures (5000 charge-depleting cycles, 15 year calendar life, and a range from À46 8C to þ66 8C) for a battery that does not fail catastrophically remains a significant challenge. [1] Recently, surface modifications of electrode materials have been explored as viable paths to improve the performance of LIBs for vehicular applications.[2] The cycle life and safety issues have been largely satisfied for Li x MO 2 (M ¼ Co, Ni, Mn, etc.) cathodes by coating the active material particles with a metal oxide and/or metal phosphate. [2a,2b,3] For anode, state-of-the-art materials such as Si suffer from significant volume expansion/contraction during charge-discharge leading to rapid capacity fade.[4] Natural graphite (NG) is a realistic candidate anode, for vehicular applications, due to its high reversible capacity, low and flat potential relative to Li/Li þ , moderate volume change, and low cost.[5] In previous reports, the performance of NG was improved by surface modifications with mild oxidation, [6] coating with amorphous carbon,[5c] metal oxides (Al 2 O 3 , ZrO 2 ), [5a,7] and metal phosphate (AlPO 4 ).[5b] These efforts were performed in order to mitigate the solid electrolyte interphase (SEI) [8] that is formed on the NG surface by reductive decomposition of the electrolyte during initial charge-discharge especially at elevated temperatures. The decomposition of the SEI at elevated temperature ($80 8C) is exothermic and initiates thermal runaway. [9] In most previous reports films of metal oxides and metal phosphates have been deposited on powder electrode materials with 'sol-gel' wet-chemical methods.