Rechargeable aqueous zinc-ion batteries (RZIBs) provide a promising complementarity to the existing lithium-ion batteries due to their low cost, non-toxicity and intrinsic safety. However, Zn anodes suffer from zinc dendrite growth and electrolyte corrosion, resulting in poor reversibility. Here, we develop an ultrathin, fluorinated two-dimensional porous covalent organic framework (FCOF) film as a protective layer on the Zn surface. The strong interaction between fluorine (F) in FCOF and Zn reduces the surface energy of the Zn (002) crystal plane, enabling the preferred growth of (002) planes during the electrodeposition process. As a result, Zn deposits show horizontally arranged platelet morphology with (002) orientations preferred. Furthermore, F-containing nanochannels facilitate ion transport and prevent electrolyte penetration for improving corrosion resistance. The FCOF@Zn symmetric cells achieve stability for over 750 h at an ultrahigh current density of 40 mA cm−2. The high-areal-capacity full cells demonstrate hundreds of cycles under high Zn utilization conditions.

The development of Li−S batteries is largely impeded by the complicated shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. In addition, the low mass loading/utilization of sulfur is another key factor that makes Li−S batteries difficult to commercialize. Here, a porous catalytic V 2 O 3 / V 8 C 7 @carbon composite derived from MIL-47 (V) featuring heterostructures is reported to be an efficient polysulfide regulator in Li−S batteries, achieving a substantial increase in sulfur loading while still effectively suppressing the shuttle effect and enhancing kinetics. Systematic mechanism analyses suggest that the LiPSs strongly adsorbed on the V 2 O 3 surface can be rapidly transferred to the V 8 C 7 surface through the built-in interface for subsequent reversible conversion by an efficient catalytic effect, realizing enhanced regulation of LiPSs from capture to conversion. In addition, the porous structure provides sufficient sulfur storage space, enabling the heterostructures to exert full efficacy with a high sulfur loading. Thus, this S−V 2 O 3 /V 8 C 7 @carbon@graphene cathode exhibits prominent rate performance (587.6 mAh g −1 at 5 C) and a long lifespan (1000 cycles, 0.017% decay per cycle). It can still deliver superior electrochemical performance even with a sulfur loading of 8.1 mg cm −2 . These heterostructures can be further applied in pouch cells and produce stable output at different folding angles (0−180°). More crucially, the cells could retain 4.3 mAh cm −2 even after 150 cycles, which is higher than that of commercial lithium-ion batteries (LIBs). This strategy for solving the shuttle effect under high sulfur loading provides a promising solution for the further development of high-performance Li−S batteries.

Characterization of the thermal properties of the surface and sub-surface structures of the skin can reveal the degree of hydration, the rate of blood flow in near-surface micro and macrovasculature, and other important physiological information of relevance to dermatological and overall health status. Here, we introduce a soft, stretchable thermal sensor, based on the so-called three omega (i.e. 3ω) method, for accurate characterization of the thermal conductivity and diffusivity of materials systems, such as the skin, that can be This article is protected by copyright. All rights reserved. 5 challenging to measure using established techniques. Experiments on skin at different body locations and under different physical states demonstrate the possibilities. Systematic studies establish the underlying principles of operation in these unusual systems, thereby allowing rational design and use of these types of devices, through combined investigations based on analytical modeling, experimental measurements and finite element analysis. The findings create broad opportunities for the use of 3ω methods in biology, with utility ranging from the integration with surgical tools or implantable devices to non-invasive uses in clinical diagnostics and therapeutics.

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