Concentration-gradient layered Li[Ni 0.8 Co 0.2 ] 0.7 [Ni 0.2 Mn 0.8 ] 0.3 O 2 oxide with Ni-rich in the core and Mn-rich in the surface region has been synthesized through a condition-controlled tank reactor reaction. While the Ni-rich core facilitates high capacity, the Mn-rich surface enables good cyclability and thermal stability. The concentration-gradient sample exhibits a higher capacity of 204 mA h g-1 at C/5 rate with superior cyclability and thermal stability compared to the constant-concentration LiNi 0.62 Co 0.14 Mn 0.24 O 2 sample, which has the same net Ni, Co, and Mn contents as those present in the concentration-gradient sample. The concentration-gradient sample was also coated with a thin layer of Al 2 O 3 on the surface to stabilize the electrode/electrolyte interface and thereby further improve the electrochemical performance. Both the structural (gradient structure) and surface (Al 2 O 3 coating) modifications help suppress side reactions between electrode and electrolyte and reduce the decline in voltage during cycling. The Al 2 O 3-coated concentration-gradient sample exhibits improved long-term cyclability, rate capability, and thermal stability compared to the pristine uncoated sample.

Cite this article as: Jin-Yun Liao and Arumugam Manthiram, High-performance Na 2 Ti 2 O 5 Nanowire Arrays Coated with VS 2 Nanosheets for Sodium-ion Storage, Nano Energy, http://dx. AbstractNa 2 Ti 2 O 5 (NTO) nanowire arrays coated with VS 2 nanosheets (NTO-VS 2 ) have been directly prepared on a current collector as a 3D anode for Na-ion batteries.Compared to graphite, the larger interlayer spacing of two dimensional VS 2 can offer facile intercalation of lithium and/or sodium ions. Aside from its natural metallic behavior, VS 2 also possesses a high theoretical capacity. The composite NTO-VS 2 nanowire arrays as an additive free 3D anode shows superior electrochemical performance compared to NTO. After 50 (C/10) and 100 (1C) cycles, the charge capacities of NTO-VS 2 are maintained, respectively, at 298 and 203 mA h g -1 , which are much higher than the values of 157 and 93 mA h g -1 observed for the same cycled Na 2 Ti 2 O 5 electrode. The higher capacity, improved rate capability, and good stability of the composite NTO-VS 2 nanowire arrays are due to the structural stability of the Na 2 Ti 2 O 5 nanowire arrays and the higher capacity and conductivity of the two-dimensional VS 2 nanosheets.

recognized as a potential substitute for the typical Pt electrode. For instance, the macroporous structure (beyond 50 nm) of carbonized sea tangle and the mesoporous structure (2-50 nm) of carbonized oak have been explored by, respectively, Grätzel's group and Gao's group. [ 5,6 ] However, the relationships between the electrochemical activity and the microstructure remain unclear and naturally derived CEs composed of micropores (less than 2 nm) have not yet been applied to DSSCs as CEs.In this communication, we present a naturally derived carbonaceous material as a Pt-free CE for DSSCs. The material was made from eggshell membranes that were recycled from domestic waste. It is found that the unique micropore-rich, hierarchically porous microstructure of eggshell membranes can effectively facilitate the charge-transfer process, leading to an improved open-circuit voltage V oc and a competitive efficiency as compared with a DSSC with a traditional Pt-based CE.Figure 1 a shows the scanning electron microscopy (SEM) image of an eggshell membrane before carbonization. It exhibits an entangled architecture of interwoven coalescing fi bers, which form a highly porous microstructure. To further enhance the electrical conductivity, the carbonized eggshell membranes were surface coated with a layer of carbon. The carbonized sucrose-coated eggshell membranes (CSEMs) were prepared by immersing the fresh eggshell membranes into a sucrose solution and then carbonizing at 800 °C. The uniformly coarsened and thickened morphology of the CSEM inThe ultimate goal of renewable solar energy is aimed at developing low-cost, high-effi ciency photovoltaic technologies that can satisfy the demand for future terawatt-scale solar energy. The dye-sensitized solar cells (DSSC), with a light-electricity conversion effi ciency exceeding 12%, are considered to be one of the most promising candidates for next-generation solar cells due to their facile assembly, cost-effectiveness, and environmental friendliness. [ 1 ] The prototypical architecture of a DSSC consists of a porous fi lm of n-type TiO 2 , a photosensitized dye, a redox couple consisting of I /I 3 − − Ielectrolyte, and a Pt counter electrode (CE). The noble and scarce nature of Pt as well as its poor stability in the electrolyte has become a signifi cant hurdle to realize low-cost, and thus, large-scale, deployment of DSSCs. Upon solar illumination, the dye molecule undergoes an electronic transition from the ground state to the excited state. This is followed by an ultrafast electron injection from the excited state of the dye molecule into the conduction band of TiO 2 , which leads to the oxidation of the dye molecule. The oxidized dye subsequently stimulates the oxidation of iodide into triiodide in the electrolyte, and the electron injected into the conduction band of TiO 2 is transported to the CE. The function of the CE is to regenerate iodide from triiodide in order to complete the light-electricity conversion process. Accordingly, the electrical properties and catalytic abi...

Three‐dimensional mesoporous TiO2‐Sn/C core‐shell nanowire arrays are prepared on Ti foil as anodes for lithium‐ion batteries. Sn formed by a reduction of SnO2 is encapsulated into TiO2 nanowires and the carbon layer is coated onto it. For additive‐free, self‐supported anodes in Li‐ion batteries, this unique core‐shell composite structure can effectively buffer the volume change, suppress cracking, and improve the conductivity of the electrode during the discharge‐charge process, thus resulting in superior rate capability and excellent long‐term cycling stability. Specifically, the TiO2‐Sn/C nanowire arrays display rechargeable discharge capacities of 769, 663, 365, 193, and 90 mA h g−1 at 0.1C, 0.5C, 2C 10C, and 30C, respectively (1C = 335 mA g−1). Furthermore, the TiO2‐Sn/C nanowire arrays exhibit a capacity retention rate of 84.8% with a discharge capacity of over 160 mA h g−1, even after 100 cycles at a high current rate of 10C.

Additive free TiO2-B/MoS2 nanowire-array 3D electrodes exhibit enhanced capacity and rate capability in Li-ion and Na-ion batteries.