One-dimensional (1D) nanostructured materials have received considerable attention for advanced functional systems as well as extensive applications owing to their attractive electronic, optical, and thermal properties. [1][2] In lithium-ion-battery science, recent research has focused on nanoscale electrode materials to improve electrochemical performance. The high surface-to-volume ratio and excellent surface activities of 1D nanostructured materials have stimulated great interest in their development for the next generation of power sources. [3][4] Materials based on tin oxide have been proposed as alternative anode materials with high-energy densities and stable capacity retention in lithium-ion batteries. [5][6][7] Various SnO 2 -based materials have displayed extraordinary electrochemical behavior such that the initial irreversible capacity induced by Li 2 O formation and the abrupt capacity fading caused by volume variation could be effectively reduced when in nanoscale form. [8][9][10] From this point of view, SnO 2 nanowires can also be suggested as a promising anode material because the nanowire structure is of special interest with predictions of unique electronic and structural properties. Furthermore, the nanowires can be easily synthesized by a thermal evaporation method. However, in its current form, this method of manufacture of SnO 2 nanowires has several limitations: it is inappropriate for mass production as high synthesis temperatures are required and there are difficulties in the elimination of metal catalysts that could act as impurities or defects. This results in reversible capacity loss or poor cyclic performance during electrochemical reactions. [11,12] The critical issues relating to SnO 2 nanowires as anode materials for lithium-ion batteries are how to avoid the deteriorative effects of catalysts and how to increase production.Herein, we report on the preparation and electrochemical performance of self-catalysis-grown SnO 2 nanowires to determine their potential use as an anode material for lithium-ion batteries. SnO 2 nanowires have been synthesized by thermal evaporation combined with a self-catalyzed growth procedure by using a ball-milled evaporation material to increase production at lower temperature and prevent the undesirable effects of conventional catalysts on electrochemical performance. The self-catalysis-grown SnO 2 nanowires show higher initial coulombic efficiency and an improved cyclic retention compared with those of SnO 2 powder and SnO 2 nanowires produced by Au-assisted growth.[11]The self-catalysis growth method, which uses a ball-milled mixture of SnO and Sn powder as an evaporation source, is appropriate for obtaining SnO 2 nanowires with high purity. The deposited products on the Si substrates contain almost 100 % of the SnO 2 nanowires formed. Observation with scanning electron microscopy (SEM) clearly shows a general view of randomly aligned SnO 2 nanowires with diameters of 200-500 nm and lengths extending to several tens of micrometers (Figure 1 a). Sn drop...

Urchin‐like CoSe2 assembled by nanorods has been synthesized via simple solvothermal route and has been first applied as an anode material for sodium‐ion batteries (SIBs) with ether‐based electrolytes. The CoSe2 delivers excellent sodiation and desodiation properties when using 1 m NaCF3SO3 in diethyleneglycol dimethylether as an electrolyte and cycling between 0.5 and 3.0 V. A high discharge capacity of 0.410 Ah g−1 is obtained at 1 A g−1 after 1800 cycles, corresponding to a capacity retention of 98.6% calculated from the 30th cycle. Even at an ultrahigh rate of 50 A g−1, the capacity still maintains 0.097 Ah g−1. The reaction mechanism of the as‐prepared CoSe2 is also investigated. The results demonstrate that at discharged 1.56 V, insertion reaction occurs, while two conversion reactions take place at the second and third plateaus around 0.98 and 0.65 V. During the charge process, Co first reacts with Na2Se to form NaxCoSe2 and then turns back to CoSe2. In addition to Na/CoSe2 half cells, Na3V2(PO4)3/CoSe2 full cell with excessive amount of Na3V2(PO4)3 has been studied. The full cell exhibits a reversible capacity of 0.380 Ah g−1. This work definitely enriches the possibilities for anode materials for SIBs with high performance.

Controlling the morphology and size of titanium dioxide (TiO(2)) nanostructures is crucial to obtain superior photocatalytic, photovoltaic, and electrochemical properties. However, the synthetic techniques for preparing such structures, especially those with complex configurations, still remain a challenge because of the rapid hydrolysis of Ti-containing polymer precursors in aqueous solution. Herein, we report a completely novel approach-three-dimensional (3D) TiO(2) nanostructures with favorable dendritic architectures-through a simple hydrothermal synthesis. The size of the 3D TiO(2) dendrites and the morphology of the constituent nano-units, in the form of nanorods, nanoribbons, and nanowires, are controlled by adjusting the precursor hydrolysis rate and the surfactant aggregation. These novel configurations of TiO(2) nanostructures possess higher surface area and superior electrochemical properties compared to nanoparticles with smooth surfaces. Our findings provide an effective solution for the synthesis of complex TiO(2) nano-architectures, which can pave the way to further improve the energy storage and energy conversion efficiency of TiO(2)-based devices.

mobile phones, and digital cameras. [1][2][3][4][5][6] Recently, LIBs have also been intensively pursued as an energy-storage technology for electrical vehicles and stationary power stations. [7][8][9][10] The reaction equations, structures, and costs of the individual components of LIBs with the common LiCoO 2 ‖polymer electrolyte‖graphite system are shown in Figure 1. It can be seen that cathode and anode materials, which serve as the most important components of LIBs, largely decide the electrochemical performance and cost of the batteries. According to the intrinsic features and reaction mechanisms of materials, four types of cathode materials and three sorts of anode materials have been investigated. [11][12][13][14][15][16] The traditional electrode material LiCoO 2 is hindered, however, by its relatively low specific capacity and the high price of Co resources, along with its inferiority in terms of environmental friendliness. LiMn 2 O 4 suffers from the Jahn-Teller distortion of Mn 3+ and the dissolution of Mn 2+ in the electrolyte, resulting in severe capacity attenuation and poor cycling performance. Graphite, as the most widely employed anode material, is limited by its finite capacity. Though Li 4 Ti 5 O 12 typically offers excellent cycle life and high safety, its relatively high potential would entail low energy density. In contrast, high-capacity Si material cannot offer long Since their successful commercialization in 1990s, lithium-ion batteries (LIBs) have been widely applied in portable digital products. The energy density and power density of LIBs are inadequate, however, to satisfy the continuous growth in demand. Considering the cost distribution in battery system, it is essential to explore cathode/anode materials with excellent rate capability and long cycle life. Nanometer-sized electrode materials could quickly take up and store numerous Li + ions, afforded by short diffusion channels and large surface area. Unfortunately, low thermodynamic stability of nanoparticles results in electrochemical agglomeration and raises the risk of side reactions on electrolyte. Thus, micro/nano and hetero/hierarchical structures, characterized by ordered assembly of different sizes, phases, and/or pores, have been developed, which enable us to effectively improve the utilization, reaction kinetics, and structural stability of electrode materials. This review summarizes the recent efforts on electrode materials with hierarchical structures, and discusses the effects of hierarchical structures on electrochemical performance in detail. Multidimensional self-assembled structures can achieve integration of the advantages of materials with different sizes. Core/yolk-shell structures provide synergistic effects between the shell and the core/yolk. Porous structures with macro-, meso-, and micropores can accommodate volume expansion and facilitate electrolyte infiltration.

Manganese based layered oxides have received increasing attention as cathode materials for sodium ion batteries due to their high theoretical capacities and good sodium ion conductivities. However, the Jahn–Teller distortion arising from the manganese (III) centers destabilizes the host structure and deteriorates the cycling life. Herein, we report that zinc-doped Na0.833[Li0.25Mn0.75]O2 can not only suppress the Jahn–Teller effect but also reduce the inherent phase separations. The reduction of manganese (III) amount in the zinc-doped sample, as predicted by first-principles calculations, has been confirmed by its high binding energies and the reduced octahedral structural variations. In the viewpoint of thermodynamics, the zinc-doped sample has lower formation energy, more stable ground states, and fewer spinodal decomposition regions than those of the undoped sample, all of which make it charge or discharge without any phase transition. Hence, the zinc-doped sample shows superior cycling performance, demonstrating that zinc doping is an effective strategy for developing high-performance layered cathode materials.