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In this work, Ca-doped lithium manganese oxides Li0.98Ca0.02Mn2O4 were successfully synthesized via a facile hydrothermal method followed by calcination. The evolution of the microstructures and electrochemical performance were investigated in detail. XRD identified that pure spinel phase with the enlarged lattice constants were observed in Ca-doped samples. SEM revealed that powders had a hollow hemispherical morphology composed of stacked nanoparticles. Ca doping can improve the electrochemical performance of LiMn2O4. Galvanostatic charge-discharge tests demonstrated that Li0.98Ca0.02Mn2O4 calcined at 550°C could deliver the initial discharge capacity of 108.6 mA h/g with the capacity retention of 91.4% after 100 cycles at 2 C. The results indicate that Ca-doped LiMn2O4 is a promising cathode material. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Zhejiang University: Science B is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The formation of tea cream in the green tea concentrates of different solid concentrations (5, 10, 20, 30, 40, 50 and 60°Brix) was investigated. The results showed a good positive correlation ( γ = 0.98, p ≤ 0.05) between the amount of tea cream and the solid concentrations from 5 to 40°Brix, while the amount of tea cream in the tea concentrates of 50 and 60°Brix decreased acutely. Total sugar, caffeine and catechins were found to be the main chemical components of tea cream in the green tea concentrate. The large decrease of the amount of tea cream in the tea concentrates of 50 and 60°Brix may be induced by a sharp increase of the viscosity of the tea concentrates, which helped to improve the stability of tea concentrate. It may be indicated that the stability of green tea concentrate enhanced when the concentration higher than 50°Brix, which helped to restrain the formation of tea cream. [ABSTRACT FROM AUTHOR]