The preparation of 2D layered SnS2 nanoplates with nanoscale lateral confinement (less than 150 nm) is described (see figure). Their unique nanoscale characteristics, including finite lateral 2D morphology, make the discharge capacity of Li ion batteries remarkably high‐almost close to the theoretical possible value.

A high-performance LiCoO 2 cathode was successively fabricated by a sol-gel coating of Al 2 O 3 to the LiCoO 2 particle surfaces and subsequent heat treatment at 600 °C for 3 h. Unlike bare LiCoO 2 , the Al 2 O 3 -coated LiCoO 2 cathode exhibits no decrease in its original specific capacity of 174 mA h/g (vs lithium metal) and excellent capacity retention (97% of its initial capacity) between 4.4 and 2.75 V after 50 cycles. A similar excellent capacity retention of the coated LiCoO 2 is also observed in a Li ion cell (C/LiCoO 2 ). This is because the high concentration of Al atoms at the particle surface region leads to the enhancement of structural stability of LiCoO 2 during cycling, which originates from the disappearance of the phase transition from a hexagonal to monoclinic phase.

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SnO 2 nanoparticles with different sizes of ∼3, ∼4, and ∼8 nm were synthesized using a hydrothermal method at 110, 150, and 200 °C, respectively. The results showed that the ∼3 nm-sized SnO 2 nanoparticles had a superior capacity and cycling stability as compared to the ∼4 and ∼8 nm-sized ones. The ∼3 nm-sized nanoparticles exhibited an initial capacity of 740 mAh/g with negligible capacity fading. The electrochemical properties of these nanoparticles were superior to those of thin-film analogues. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed that the ∼3 nm-sized SnO 2 nanoparticles after electrochemical tests did not aggregate into larger Sn clusters, in contrast to those observed with the ∼4 and ∼8 nm-sized ones.

Hierarchically porous carbon-coated ZnO quantum dots (QDs) (~3.5 nm) were synthesized by a one-step controlled pyrolysis of the metal-organic framework IRMOF-1. We have demonstrated a scalable and facile synthesis of carbon-coated ZnO QDs without agglomeration by structural reorganization. This unique microstructure exhibits outstanding electrochemical performance (capacity, cyclability, and rate capability) when evaluated as an anode material for lithium ion batteries.

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The hard cell! There have been numerous reports highlighting the questionable safety of lithium secondary batteries, an example of which is shown here, where exothermic reactions of LiCoO2 electrodes have considerable fire and explosion potential. The coating of such electrodes with a layer of AlPO4 nanoparticles is shown to reduce these risks significantly, even where a short circuit of the cell was observed.

Two-dimensional crystals, which possess a nanoscale dimension only in the c axis and have infinite length in the plane, have been emerging as important new materials owing to their unique properties and potential applications in areas ranging from electronics to catalysis. [1][2][3][4][5] In particular, recent developments of 2D nanosheet crystals such as stable graphene and transition-metal chalcogenides (TMCs) have sparked new discoveries in condensed-matter physics and electronics.[6] Further miniaturization of these 2D structures by lateral confinements can potentially bring not only the modulation of electron-transport phenomena [7] but also the enhancement of their 2D host capabilities which arise from the enlarged surface area and improved diffusion processes upon the intercalation of guest molecules.[8] However, synthetic routes for such laterally confined 2D crystals, especially for TMCs, have been challenging since they are unstable and immediately scroll up into closed structures such as quasi-0D onions or 1D tubes owing to increased peripheral dangling bonds. [9][10][11] Herein, we have developed an entirely new "shapetransformation" concept that proceeds by a rolling out of 1D tungsten oxide nanorods for the fabrication of laterally confined (less than 100 nm) 2D WS 2 nanosheet crystals. Here, a surfactant-assisted low-temperature (lower than 350 8C) solution process is also critical in stabilizing 2D nanosheet structures as opposed to conventional high-temperature (higher than 700 8C) gas-solid routes which yield only 0D or 1D structures. [12][13][14] Our 2D WS 2 nanosheet crystals are synthesized from tungsten oxide (W 18 O 49 ) nanorods [15,16] in the presence of carbon disulfide in hot hexadecylamine solution.Figure 1 a shows an overview of our shape-transformation scheme for the generation of 2D WS 2 nanosheet crystals from the tungsten oxide rods. The reaction between the carbon disulfide and hexadecylamine generates in situ hydrogen disulfide and hexadecylisothiocyanate via N-hexadecyldithiocarbamate as a transient species [Eq. (1); see also Figures S1 and S2 in the Supporting Information], and subsequent