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Transition metal chalcogenides represent a class of the most promising alternative electrode materials for high-performance lithium-ion batteries (LIBs) owing to their high theoretical capacities. However, they suffer from large volume expansion, particle agglomeration, and low conductivity during charge/discharge processes, leading to unsatisfactory energy storage performance. In order to address these issues, we rationally designed three-dimensional (3D) hybrid composites consisting of ZnSe nanodots uniformly confined within a N-doped porous carbon network (ZnSe ND@N-PC) obtained via a convenient pyrolysis process. When used as anodes for LIBs, the composites exhibited outstanding electrochemical performance, with a high reversible capacity (1,134 mA·h·g at a current density of 600 mA·g after 500 cycles) and excellent rate capability (696 and 474 mA·h·g at current densities of 6.4 and 12.8 A·g, respectively). The significantly improved lithium storage performance can be attributed to the 3D architecture of the hybrid composites, which not only mitigated the internal mechanical stress induced by the volume change and formed a 3D conductive network during cycling, but also provided a large reactive area and reduced the lithium diffusion distance. The strategy reported here may open a new avenue for the design of other multifunctional composites towards high-performance energy storage devices. [ABSTRACT FROM AUTHOR]

NaAlH 4 is a promising anode material for lithium-ion batteries due to its high theoretical capacity of 1985 mAh g −1 . However, the practical application of NaAlH 4 anode is hindered by its low charge reversibility and poor cycle performance. To improve the Li-storage performance of NaAlH 4 anode, the regeneration and degradation mechanism of NaAlH 4 have been revealed in this work. Firstly, the results show that decreasing the crystalline size would result in the direct regeneration of NaAlH 4 from Na and Al without any intermediate phases (such as LiNa 2 AlH 6 ), which dramatically enhances the reversibility of NaAlH 4 anode. Secondly, a new cycle degradation mechanism is demonstrated that NaAlH 4 would decompose above 1.42 V during the charge process, which leads to a rapid degradation of cycle capacity. Therefore, the reversible capacity of NaAlH 4 anode after 20 cycles could be significantly increased from 89 mAh g −1 to 456 mAh g −1 by decreasing the cut-off voltage from 3 V to 1 V, showing an improved cycle stability. [ABSTRACT FROM AUTHOR]

Li 3 VO 4 anchored 3D graphene networks (Li 3 VO 4 /3DGNs) nanocomposite was constructed via a facile one-pot hydrothermal method. The as-prepared Li 3 VO 4 /3DGNs nanocomposite exhibits a unique pomegranate-like structure where nanohole-dotted Li 3 VO 4 nanoparticles resembling pomegranate seeds are firmly anchored and uniformly distributed on 3DGNs. Li 3 VO 4 /3DGNs composite presents excellent cycling and rate performance. The initial reversible capacity is 397 mAh g −1 at 2 A g −1 and remains at 259 mAh g −1 even after 2500 cycles. In addition, under current densities of 0.2, 0.4, 0.8, 2, 4, 8, 16 and 32 A g −1 , the composite delivers large capacities of 471, 404, 359, 318, 290, 247, 191 and 142 mAh g −1 , respectively. The excellent electrochemical performance is mainly attributed to the enhanced electrical conductivity and structural stability as well as accelerated Li + diffusion derived from both the 3D continuous conductive channels endowed robust 3DGNs and the nanohole-dotted Li 3 VO 4 nanoparticles. [ABSTRACT FROM AUTHOR]