Search

Abstract: Ag3CuS2 nanocages were successfully fabricated for the first time via a convenient ion-exchange route by Ag+ reacting with Cu7S4 18-facet hollow nanopolyhedra. The average size and shell thickness of Ag3CuS2 nanocages were around 400 and 30nm, respectively. Room-temperature response of Ag3CuS2 nanocages to ammonia was investigated by photoluminescence-type sensor. Sensing results suggested that these hollow-structured Ag3CuS2 exhibited better performances including higher sensitivity, shorter response and recovery time than their rod-shape counterparts. A possible hole trapping mechanism was proposed. [Copyright &y& Elsevier]

• A PVP-bridged coating strategy was designed to prepare the LMR@γ-LAO composite. • γ-LiAlO 2 coating layer leads to a higher Li+ diffusion coefficient of the cathode. • γ-LiAlO 2 coating layer enhances the thermal stability of the cathode. • DFT calculation proves a lower Li+ diffusion energy barrier in γ-LiAlO 2. Li-rich layered materials have been considered as promising cathode materials for next-generation lithium-ion batteries due to their high capacity (≥250 mAh g−1). Unfortunately, this type of cathode material still suffers from intrinsic deficiencies of capacity fading and side reactions. Surface coating with a protective layer can resolve the above problems to some extent, whereas normal coating strategies still suffer from process complexity and are difficult to prevent phase separation that leads to the formation of an independent miscellaneous phase. Herein, we report an effective PVP-bridged coating method, in which the PVP molecules can bridge the gap between the coating shell and the electrode material core through hydrogen bonding and functional groups. Utilizing this strategy, a uniform Li-ion conductor γ-LiAlO 2 nanolayer with a thickness of 7 nm is successfully formed on the surface of the Li 1.2 Ni 0.182 Co 0.08 Mn 0.538 O 2 cathode material, which leads to an excellent rate capability (177.0 mAh g−1 delivered at 5 C) and superior cycling stability (89.3% capacity retention achieved after 100 cycles at 10 C) for the composite material. Furthermore, the exothermic reaction for the composite material takes place at a higher temperature (234.1 °C) relative to the uncoated sample (220.9 °C), implying its improved thermal stability. Galvanostatic intermittent titration technique and density functional theory calculation demonstrate a higher Li+ diffusion coefficient for the γ-LiAlO 2 coated sample and a lower Li+ diffusion energy barrier in γ-LiAlO 2. Based on the promising results, the PVP-bridged coating strategy presented in this study provides a new perspective in material design towards high-performance Li-rich cathode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Lithium-rich layered compound cathode materials recently attract ever-growing attention in lithium ion batteries for electric vehicles and energy storage devices due to their high discharge capacities of over 250 mAh g −1 and low cost. However, they still suffer from capacity fade, voltage decay and poor rate capability and thermal stability. In this paper, the Al&F co-doped Li 1.2 Ni 0.13 Co 0.13- x Mn 0.54 Al x O 2(1- y ) F 2 y cathode material has been successfully prepared via a co-precipitation reaction and a subsequent solid phase calcination. The resulting material combines the advantages of both Al-doping and F-doping, which can effectively mitigate the intrinsic layered-to-spinel phase transformation, and as a consequence, inhibits the capacity fade and voltage decay: delivering a discharge capacity of 217 mAh g −1 with retention of 88.21% and an average discharge voltage decay of 0.4019 V upon 150 cycling at 0.5 C. On the other side, with an increased electronic and ionic conductivity, this co-doping practice enhances the rate capability by a considerable extent that it delivers a discharge capacity of 157 mAh g −1 at 10 C, thus facilitating its application for quick charging devices. In addition, the thermal stability related with battery safety is significantly meliorated. Specifically, the co-doped cathode material exhibits an initial exothermal peak at a higher temperature of 273 °C and a much less overall heat generation of 221 J g −1 compared to the 210 °C and 755 J g −1 for the pristine one. In conclusion, the anion/cation co-substitution strategy has been demonstrated to be of great promise for the improvement of lithium-rich layered cathode materials. [ABSTRACT FROM AUTHOR]

We design and successfully synthesize non-fluorinated polyamides with controlled crosslinking using sulfonimide as a bi-functional linker to interconnect polymer backbones and as a bridge for proton conduction. We show that the bi-functional linkers are highly beneficial not only for mechanical enforcement of the proton exchange membranes but also for enhancement of water retention capacity. With an appropriate degree of crosslinking, higher water retention capacity than that of commercial Nafion membranes can be obtained. The maximum proton conductivity of the membranes is found to be as high as 0.139 S cm −1 at 80 °C, almost the same as that of a Nafion 117 membrane. Excellent performance with the bi-functional polymer membranes in an air-breathing direct methanol fuel cell prototype, comparable to the performance of a Nafion 117 membrane, is demonstrated. [ABSTRACT FROM AUTHOR]