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Tin‐based hybrid flow batteries have demonstrated dendrite‐free morphology and superior performance in terms of cycle life and energy density. However, the quick accumulation of electrodeposits near the electrode/membrane interface blocks the ion transport pathway during the charging of the battery, resulting to a very limited areal capacity (especially at high current density) that significantly hinders its deployment in long‐duration storage applications. Herein, a conductivity‐activity dual‐gradient design is disclosed by electrically passivating the carbon felt near the membrane/electrode interface and chemically activating the carbon felt near the electrode/current collector interface. In consequence, the tin metals are preferentially plated at the region near electrode/current collector, preventing the ion transport pathway from being easily blocked. The resultant gradient electrode demonstrated an unprecedentedly high areal capacity of 268 mAh cm−2 at a current density of as high as 80 mA cm−2. Numerical modeling and experimental characterizations show that the dual‐gradient electrode differs from conventional electrodes with regard to their reaction current density distribution and electrodeposit distribution during charging. This work demonstrates a new design strategy of 3D electrodes for hybrid flow batteries to induce a desirable distribution of electrodeposits and achieve a high areal capacity at commercially relevant current densities. [ABSTRACT FROM AUTHOR]

In the present work, a flexible carbon sponge is experimentally characterized and proposed as an alternative electrode for advanced vanadium redox flow batteries. Such an electrode is prepared via directly carbonizing the commercially‐available and inexpensive melamine formaldehyde resin sponge in argon, to inherit the well‐defined and three‐dimensional bi‐continuous architecture of the melamine sponge with 99.6% porosity and 40 μm average pore size. By applying the carbon sponges as the electrodes, it is demonstrated that the vanadium flow battery at 200 mA cm−2 can yield an energy efficiency of 77.9%, significantly higher than that with commonly‐used graphite felt electrodes (72.9%). After a thermal treatment in air, the energy efficiency of carbon sponge can further be improved to 81.2% at mA cm−2 due to introduction of favorable oxygen containing functionalities. The operating stability with the carbon sponge is proven by a 200 cycling test with minor efficiency decay. [ABSTRACT FROM AUTHOR]

Hydrogels have been widely applied in the fields of biology, medicine, soft materials and flexible/wearable devices owing to their superior biocompatibility and their versatile physicochemical properties. Although multiple chemical and physical methods have been proposed to functionalize hydrogels, endowing hydrogels with multi-properties/functionalities utilizing few components is still a challenge. This paper describes a simple and effective method to functionalize polymeric hydrogels with carboxymethyl cellulose (CMC) modified Fe3O4 nanoparticles (CMC@Fe3O4 NPs). The as-prepared metallogels exhibit good self-healing ability, ionic conductivity, photo-thermal transformability and magnetic field responsiveness. A triple functional sensor was built up to prove the universal viability of this metallogel toward functional devices. [ABSTRACT FROM AUTHOR]

Observations and model results indicate that the quasi-biennial oscillation (QBO) modulation of stratospheric water vapor results from two causes. Dynamical redistribution of water vapor from the QBO-induced mean meridional circulation dominates the observed variability in the middle and upper stratosphere. In the lower stratosphere, the QBO water vapor variability is dominated by a 'tape recorder' that results from the dehydration signal accompanying the QBO variation of the tropical cold point tropopause. It is suggested that another low frequency tape recorder exists due to ENSO modulations of the tropical tropopause, but insufficiently long observations of stratospheric water vapor exist to identify this in the observations.

A model of the long-range transport and deposition of sulfur dioxide is used to develop a policy for regional acid rain control in eastern China. Maps of eastern China show sulfur emission sources taken from a Chinese Research Academy of Environmental Sciences database, and policy goals are set for each province.