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This work proposes a Si–O bond strategy to enhance the electrochemical stability of solvents, pioneering the direction of less-fluorinated electrolytes for eco-friendly and practical Li metal batteries.

An all-passive water-cooling assisted vapor condensation device was developed for easy integration with an interfacial evaporator to form an efficient solar purifier device.

Self-purifying electrolyte effectively eliminates the reactive pernicious species and endows high energy Li ion batteries with stable long-term cycling.

Electrolyte engineering advances Li metal batteries (LMBs) with high Coulombic efficiency (CE) by constructing LiF-rich solid electrolyte interphase (SEI). However, the low conductivity of LiF disturbs Li

Novel biocomposite aerogels with Janus character are fabricated for application as interfacial evaporators, using cellulose nanofibrils (CNFs) as building blocks and Ti3C2Tx MXenes as functional fillers via pre-freezing, solvent exchange, unidirectional freeze-casting, and freeze-drying. The upper and lower parts of the Janus CNF/MXene composite aerogels (JCM aerogels) exhibit opposite wettabilities and perform complementary functions. The lower part of the aerogel is a hydrophilic CNF aerogel for enabling continuous upward water transport. The function of the upper part, a silane-modified hydrophobic CNF/MXene aerogel, is photothermal conversion and heat insulation for efficient evaporation of water. The JCM aerogels self-float stably on the water surface and achieve a high evaporation rate of 2.287 kg m−2 h−1 at an efficiency of 88.2% under 1 sun illumination. Numerical simulations for heat and mass transfer confirm the synergy between the two parts of the composites, which enabled the excellent evaporation performance observed. In addition, the JCM aerogels showed excellent salt resistance and seawater durability in simulated solar-driven desalination experiments. The design of these interfacial evaporators may offer new insights for developing reliable and environmentally friendly water purification technologies.

The independent expertise required by the preparation and application of graphene has brought a challenge to the more fluent development of graphene devices. We combine the advantages of chemical vapor deposition and micromechanical exfoliation methods of synthesizing graphene to develop a "graphene tape" for the fast utilization of graphene, which is robust, storable, and user-friendly. Prepared by pretransferring graphene to the surface of a polymer carrier film with weak interfacial adhesion, this graphene tape enables the acquisition, patterning, and layer-by-layer epitaxy of scalable graphene on a target substrate through simple cutting, pressing, and peeling off. Multiple characterizations demonstrate its comparable quality with as-synthesized graphene even after stored for over 30 days, overcoming the time and space limitations of acquiring a graphene sample. We believe that this graphene tape can bridge the current gap between graphene synthesis and applications and promote industrial progress of graphene-based devices in the post-Moore era.

Creating long-lived topological textured liquid crystals (LCs) in confined nonspherical space is of significance in both generations of structures and fundamental studies of topological physics. However, it remains a great challenge due to the fluid character of LCs and the unstable tensional state of transient nonspheres. Here, we realize a rich series of topological textures confined in nonspherical geometries by drop impact assembly (DIA) of graphene oxide (GO) aqueous LCs. Various highly curved nonspherical morphologies of LCs were captured by gelator bath, generating distinct out-of-equilibrium yet long-lived macroscopic topological textures in 3D confinement. Our hydrodynamic investigations on DIA processes reveal that the shear-thinning fluid behavior of LCs and the arrested GO alignments mainly contribute to the topological richness in DIA. Utilizing the shaping behavior of GO LCs compared to other conventional linear polymers such as alginate, we further extend the DIA methodology to design more complex yet highly controllable functional composites and hybrids. This work thus reveals the potential to scale production of uniform yet anisotropic materials with rich topologic textures and tailored composition.

Spherical capsules are widely used as housing for phase change materials (PCMs) in heat exchangers for thermal energy storage applications. In view of the low thermal conductivity of common PCM candidates, extended surfaces, such as fins, are routinely added to PCM capsules to improve the thermal performance. In this paper, to quantitatively evaluate the influence of fins on the thermal performance of PCM-filled spherical capsules, constrained melting heat transfer of a PCM in a circumferentially finned spherical capsule with various fin heights was investigated both numerically and experimentally under constant-temperature boundary conditions. The enthalpy-based model was used in the numerical simulations to deal with phase change, while the control volume method was used to solve the governing equations for the melting problem with natural convection in the liquid phase. A spherical melting facility that allows for direct observation of the solid-liquid phase interface during melting was designed and constructed. The spherical capsule and fins were made of glass and aluminum, respectively. Octadecane with a nominal melting point at 28.2°C was used as the PCM. Qualitative agreement was obtained between the experimentally observed and numerically predicted results of solid-liquid interface evolution. The sources of the differences were identified to be the departure of the physical model from the real system, as well as simplifications of the numerical model. The evolution of the natural convective flow and temperature fields during melting are presented in the form of a series of snapshots of streamline and isotherm contours. The heat transfer mechanisms during melting were interpreted by these contour snapshots. The presence of circumferential fins not only enhances heat conduction, but also augments natural convection heat transfer in localized areas in the vicinity of the fins. The localized interactions between these two effects are significantly affected by the fin height. Under the specific conditions considered, fins with height-to-radius ratios of 0.25, 0.50, and 0.75 decrease the total melting time by 10.6%, 20.2%, and 28.7%, respectively, leading to a significant increase of the thermal energy storage rates in the spherical capsule. Although the presence of fins benefits heat transfer enhancement, a more comprehensive understanding of the effects of other important factors, such as the inclination angle of the spherical capsule, is required.

Computational analysis of transient phenomenon followed by the periodic state of laminar flow and heat transfer due to a rectangular rotating object in a square cavity is investigated. A finite-volume-based fixed-grid/sliding mesh computational methodology utilizing primitive variables is used. Rectangular rotating objects with different aspect ratios (AR = 1, 2, 3, 4) are placed in the middle of a square cavity. The motionless object is set in rotation at time t = 0 with a constant angular velocity. For the insulated and isothermal objects, the cavity is maintained as differentially-heated and isothermal enclosures, respectively. Natural convection heat transfer is neglected. For a given shape of the object and a constant angular velocity, a range of rotating Reynolds numbers are covered for a Pr = 5 fluid. The Reynolds numbers were selected so that the flow field is not affected by the Taylor instabilities (Ta < 1750). The periodic flow field, the interaction of the rotating objects with the recirculating vortices at the four corners and the periodic channelling effect of the traversing vertices are clearly elucidated. The corresponding thermal fields in relation to the evolving flow patterns and the skewness of the temperature contours in comparison to conduction-only case were discussed. The skewness is observed to become more marked as the Reynolds number is lowered. Transient variations of the average Nusselt numbers of the respective systems show that for high Re numbers, a quasi-periodic behavior due to the onset of the Taylor instabilities is dominant, whereas for low Re numbers, periodicity of the system is clearly observed. Time-integrated average Nusselt numbers of the insulated and isothermal object systems were correlated to the rotational Reynolds number and the aspect ratio of the rectangle. For high Re numbers, the performance of the system is independent of the aspect ratio. On the other hand, with lowering of the hydraulic diameter (i.e. bigger objects), objects with the highest and lowest aspect ratios exhibit the highest and lowest heat transfer, respectively. High intensity of the periodic channelling and not its frequency are identified as the cause of the observed enhancement.