The tributylphenyltin (TBPT)-encapsulated resorcinol (R)-formaldehyde (F) sol was prepared inside the micelles of cetyltrimethylammonium bromide (CTAB). This core-shell-type sol was polymerized and further carbonized to obtain nanosized Sn-encapsulated spherical hollow carbon. The size of spherical hollow carbon and Sn metal particles was controllable by changing the R/CTAB or TBPT/CTAB mole ratio, respectively. It is likely that, when tested as the anode in Li secondary batteries, the spherical hollow carbon acts as a barrier to prevent the aggregation of nanosized Sn particles and provides a void space for Sn metal particles to experience a volume change without a collapse of carbon shell, giving rise to a better cycle performance than that of pure Sn metal.

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.

Sn4 P3 is introduced for the first time as an anode material for Na-ion batteries. Sn4 P3 delivers a high reversible capacity of 718 mA h g(-1), and shows very stable cycle performance with negligible capa-city fading over 100 cycles, which is attributed to the confinement effect of Sn nanocrystallites in the amorphous phosphorus matrix during cycling.

To deploy Li-ion batteries in next-generation vehicles, it is essential to develop electrodes with durability, high energy density, and high power. Here we report a breakthrough in controlled full-electrode nanoscale coatings that enables nanosized materials to cycle with durable high energy and remarkable rate performance. The nanoparticle electrodes are coated with Al(2)O(3) using atomic layer deposition (ALD). The coated nano-LiCoO(2) electrodes with 2 ALD cycles deliver a discharge capacity of 133 mAh/g with currents of 1400 mA/g (7.8C), corresponding to a 250% improvement in reversible capacity compared to bare nanoparticles (br-nLCO), when cycled at this high rate. The simple ALD process is broadly applicable and provides new opportunities for the battery industry to design other novel nanostructured electrodes that are highly durable even while cycling at high rate.