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Binary metal sulfides have been widely studied as anode materials for lithium-ion batteries (LIBs) due to their abundant charge-storage oxidation reduction states. However, their poor electrochemical stability due to their volume expansion and poor electrical conductivity has hindered their commercial application. Here, we report a MOFs (Metal–organic frameworks)-derived strategy for the synthesis of stable hybrid structures with NiCo2S4 nanocrystals in nitrogen-doped carbon nanorods (represented as NiCo2S4@N–C). NiCo2S4@N–C with many interconnecting voids to reduce volume expansion and increase the contact area between the material and the electrolyte. In addition, the doping of nitrogen atoms in the carbon matrix can improve the conductivity of the electrode material and increase the active site, thus changing the electrochemical performance of the electrode material. As expected, NiCo2S4@N–C still has a large reversible capacity of 1543 mAh g−1 after 100 cycles compared to CoS2@N–C and NiS@N–C at 100 mA g−1 current densities, and even at a large current density of 1 A g−1, the capacity still retains 893 mAh g−1 after 1000 cycles, showing enhanced lithium storage performance, indicating its potential as anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Nickel(Ni)-rich layered materials have attracted considerable interests as promising cathode materials for lithium ion batteries (LIBs) owing to their higher capacities and lower cost. Nevertheless, Mn-rich cathode materials usually suffer from poor cyclability caused by the unavoidable side-reactions between Ni4+ ions on the surface and electrolytes. The design of gradient concentration (GC) particles with Ni-rich inside and Mn-rich outside is proved to be an efficient way to address the issue. Herein, a series of LiNi0.6Co0.2Mn0.2O2 (LNCM622) materials with different GCs (the atomic ratio of Ni/Mn decreasing from the core to the outer layer) have been successfully synthesized via rationally designed co-precipitation process. Experimental results demonstrate that the GC of LNCM622 materials plays an important role in their microstructure and electrochemical properties. The as-prepared GC3.5 cathode material with optimal GC can provide a shorter pathway for lithium-ion diffusion and stabilize the near-surface region, and finally achieve excellent electrochemical performances, delivering a discharge capacity over 176 mAh·g−1 at 0.2 C rate and exhibiting capacity retention up to 94% after 100 cycles at 1 C. The rationally-designed co-precipitation process for fabricating the Ni-rich layered cathode materials with gradient composition lays a solid foundation for the preparation of high-performance cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

Significance Single- and double-walled anatase TiO2 nanovesicles have been, respectively, prepared by a template-free hydrothermal treatment of Ti(SO4)2 with H2O2 and urea. Photocatalytic degradation of Rhodamine B indicates that double-walled TiO2 nanovesicles have an initial lower but a final higher photocatalytic efficiency than single-walled ones. All nanovesicles have significantly lower performance than commercially available P25 TiO2. The enhanced capacity for UV light absorption and· OH radicals production, large specific surface area, and unique hierarchical hollow architectures contribute to the enhanced photocatalytic activity and improved feasibility of anatase TiO2 nanovesicles for engineering applications. © 2015 American Institute of Chemical Engineers AIChE J, 61: 1478-1482, 2015 [ABSTRACT FROM AUTHOR]