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We have reported for the first time the preparation of yolk-shell-structured Li4Ti5O12 powders for use as anode materials in lithium-ion batteries. One Li4Ti5O12 yolk-shell-particle powder is directly formed from each droplet containing lithium, titanium, and carbon components inside the hot wall reactor maintained at 900 °C. The precursor Li4Ti5O12 yolk-shell-particle powders, which are directly prepared by spray pyrolysis, have initial discharge and charge capacities of 155 and 122 mA h g−1, respectively, at a current density of 175 mA g−1. Post-treatment of the yolk-shell-particle powders at temperatures of 700 and 800 °C improves the initial discharge and charge capacities. The initial discharge capacities of the Li4Ti5O12 powders with a yolk-shell structure and a dense structure post-treated at 800 °C are 189 and 168 mA h g−1, respectively. After 100 cycles, the corresponding capacities are 172 and 152 mA h g−1, respectively (retentions of 91 and 90 %). [ABSTRACT FROM AUTHOR]

Several yolk-shell-structured CuO-Fe2O3 powders with various Cu/Fe molar ratios have been successfully prepared under equivalent reaction conditions using a one-pot spray pyrolysis process. The Cu and Fe components are uniformly distributed throughout the powders, irrespective of composition. The Brunauer-Emmett-Teller surface areas of the yolk-shell CuO-Fe2O3 systems increased from 5 to 16 m2 g−1 if the Cu/Fe molar ratios are decreased from 3:1 to 1:3. The initial discharge and charge capacities of the yolk-shell CuO-Fe2O3 system (Cu/Fe=1:2), showing maximum values at a constant current density of 1000 mA g−1, are 1436 and 1012 mA h g−1, respectively. After 130 cycles, the discharge capacities of the yolk-shell CuO-Fe2O3 powders with Cu/Fe molar ratios of 1:3, 1:2, 1:1, 2:1, and 3:1 are 1159, 1151, 755, 655, and 651 mA h g−1, respectively. The discharge capacities of the yolk-shell and dense powder samples after 50 cycles, when subjected to a series of current density increases from 500 to 5000 mA g−1, are 735 and 495 mA h g−1, respectively. [ABSTRACT FROM AUTHOR]

Pure LiCoO2 nanopowders and those coated with lithium boron oxide (LBO) glass are prepared directly using high-temperature flame spray pyrolysis. Prior to post-treatment, the LiCoO2 powders with nanometer-size particles have low discharge capacities and poor cycle properties, irrespective of the amount of glass material. Post-treatment at 500 °C does not improve these properties significantly; however, the LBO glass-modified LiCoO2 powders post-treated at 600 and 700 °C demonstrates good cycle performance. The discharge capacity of the 5 wt% glass-modified LiCoO2 powders post-treated at 600 °C with a mean particle size of 120 nm, decreases from 122 to 109 mAh g−1 after 50 cycles, with a capacity retention of 89%. The capacity retentions of the pure and 2, 5, and 10 wt% glass-modified LiCoO2 powders post-treated at 700 °C are 86, 96, 98, and 98% after 50 cycles, respectively. [ABSTRACT FROM AUTHOR]

We have reported for the first time the preparation of yolk-shell-structured Li4Ti5O12 powders for use as anode materials in lithium-ion batteries. One Li4Ti5O12 yolk-shell-particle powder is directly formed from each droplet containing lithium, titanium, and carbon components inside the hot wall reactor maintained at 900 °C. The precursor Li4Ti5O12 yolk-shell-particle powders, which are directly prepared by spray pyrolysis, have initial discharge and charge capacities of 155 and 122 mA h g(-1) , respectively, at a current density of 175 mA g(-1) . Post-treatment of the yolk-shell-particle powders at temperatures of 700 and 800 °C improves the initial discharge and charge capacities. The initial discharge capacities of the Li4Ti5O12 powders with a yolk-shell structure and a dense structure post-treated at 800 °C are 189 and 168 mA h g(-1) , respectively. After 100 cycles, the corresponding capacities are 172 and 152 mA h g(-1) , respectively (retentions of 91 and 90%)., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)