Zn‐based batteries are safe, low cost, and environmentally friendly, as well as delivering the highest energy density of all aqueous battery systems. However, the application of Zn‐based batteries is being seriously hindered by the uneven electrostripping/electroplating of Zn on the anodes, which always leads to enlarged polarization (capacity fading) or even cell shorting (low cycling stability). How a porous nano‐CaCO3 coating can guide uniform and position‐selected Zn stripping/plating on the nano‐CaCO3‐layer/Zn foil interfaces is reported here. This Zn‐deposition‐guiding ability is mainly ascribed to the porous nature of the nano‐CaCO3‐layer, since similar functionality (even though relatively inferior) is also found in Zn foils coated with porous acetylene black or nano‐SiO2 layers. Furthermore, the potential application of this strategy is demonstrated in Zn|ZnSO4+MnSO4|CNT/MnO2 rechargeable aqueous batteries. Compared with the ones with bare Zn anodes, the battery with a nano‐CaCO3‐coated Zn anode delivers a 42.7% higher discharge capacity (177 vs 124 mAh g−1 at 1 A g−1) after 1000 cycles.

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As a promising anode for aqueous batteries, Zn metal shows a number of attractive advantages such as low cost, low redox potential, high capacity, and environmental benignity. Nevertheless, the quick growth of dendrites/protrusions on the “hostless” Zn anodes not only enlarges batteries’ internal resistance but also causes sudden shorting failure by piercing separators. Herein, we report a novel heterogeneous seed method to guide the morphology evolution of plated Zn. The heterogeneous seeds are sputtering-deposited quasi-isolated nano-Au particles (Au-NPs) that enable a uniform and stable Zn-plating/stripping process on the anodes. Tested on Zn|Zn symmetric cells, the Au-nanoparticle (NP) decorated Zn anodes (NA-Zn) demonstrate much better cycling stability than the bare ones (92 vs 2000 h). In NA-Zn|CNT/MnO2 batteries, this heterogeneous seed prolongs the lifetime of the device from ∼480 cycles up to 2000 cycles. This work offers a facile and promising Zn dendrite/protrusion suppressing route for the achievement of long-life Zn-ion batteries.

Nanoporous thermochromic VO(2) films with low optical constants and tunable thicknesses have been prepared by polymer-assisted deposition. The film porosity and thickness change the interference relationship of light reflected from the film-substrate and the air-film interfaces, strongly influencing the optical properties of these VO(2) films. Our optimized single-layered VO(2) films exhibit high integrated luminous transmittance (T(lum,l) = 43.3%, T(lum,h) = 39.9%) and solar modulation (ΔT(sol) = 14.1%, from T(sol,l) = 42.9% to T(sol,h) = 28.8%), which are comparable to those of five-layered TiO(2)/VO(2)/TiO(2)/VO(2)/TiO(2) films (T(lum,l) = 45%, T(lum,h) = 42% and ΔT(sol) = 12%, from T(sol,l) = 52% to T(sol,h) = 40%, from Phys. Status Solidi A2009, 206, 2155-2160.). Optical calculations suggest that the performance could be further improved by increasing the porosity.

This paper describes a solution-phase synthesis of high-quality vanadium dioxide thermochromic thin films. The films obtained showed excellent visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal-insulator phase transition (MIPT). For a 59 nm thick single-layer VO(2) thin film, the integral values of visible transmittance (T(int)) for metallic (M) and semiconductive (S) states were 54.1% and 49.1%, respectively, while the NIR switching efficiencies (DeltaT) were as high as 50% at 2000 nm. Thinner films can provide much higher transmittance of visible light, but they suffer from an attenuation of the switching efficiency in the near-infrared region. By varying the film thickness, ultrahigh T(int) values of 75.2% and 75.7% for the M and S states, respectively, were obtained, while the DeltaT at 2000 nm remained high. These results represent the best data for VO(2) to date. Thicker films in an optimized range can give enhanced NIR switching efficiencies and excellent NIR blocking abilities; in a particularly impressive experiment, one film provided near-zero NIR transmittance in the switched state. The thickness-dependent performance suggests that VO(2) will be of great use in the objective-specific applications. The reflectance and emissivity at the wavelength range of 2.5-25 microm before and after the MIPT were dependent on the film thickness; large contrasts were observed for relatively thick films. This work also showed that the MIPT temperature can be reduced simply by selecting the annealing temperature that induces local nonstoichiometry; a MIPT temperature as low as 42.7 degrees C was obtained by annealing the film at 440 degrees C. These properties (the high visible transmittance, the large change in infrared transmittance, and the near room-temperature MIPT) suggest that the current method is a landmark in the development of this interesting material toward applications in energy-saving smart windows.

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