A Novel Adsorbent Prepared by Aluminum-Containing Waste Residue and Its Application for Congo Red Wastewater Decolorization

Modified aluminum slag (MAS) was applied as an adsorbent for Congo red (CR) prepared by the hydrothermal treatment of Ca(OH)2. At 25°C, with a MAS dosage of 0.3 g, initial CR concentration of 100 mg/L and initial pH = 5, and the adsorption time was 40 min, the CR removal efficiency was 98.41%. The adsorption trend of CR conformed to the second-order kinetics, and the adsorption isotherm follows the Freundlich isotherm model. Compared with RAS, MAS has a larger pore volume and specific surface area. The mechanism of action of MAS on CR was the interaction between membrane diffusion and internal diffusion, and the adsorption rate during the membrane diffusion was the fastest.

A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices,gel polymer electrolytes(GPEs)are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability.Here,an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation,in which N-doped carbon quantum dots(N-CQDs)and TiO2are introduced as photocatalysts and additives to improve the performances of GPEs.Specifically,N-CQDs participate as a cross-linker to construct the inner porous structure,and TiO2nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage(3.5 V).The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors(SCs).This GPE based SC not only exhibits prominent rate performance(105%capacitance retention at the current density of 40A g^(-1))and cyclic stability(85%at 1 A g^(-1)under 3.5 V after 20,000 cycles),but also displays remarkable energy density(42.88 Wh kg^(-1))with high power density(19.3 k W kg^(-1)).Moreover,the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

Electrode structure enabling dendrite inhibition for high cycle stability quasi-solid-state lithium metal batteries

Lithium(Li)metal batteries(LMBs)are widely regarded as the ultimate choice for the next generation of high-energy–density batteries.However,the uncontrollable growth of Li dendrites formed by inhomogeneous deposition seriously hinders its commercialization.Although many studies have achieved significant results in inhibiting the formation of Li dendrites,it is still impossible to eradicate them completely.Therefore,regulating the deposition behavior,such as the growth direction of unevenly deposited Li,is preferable to unilaterally suppressing them in some cases.Here we report a structured anode that can confine the deposited Li within holes and tune it to become vertical-up/horizontal-centripetal mixed growth mode by optimizing the electric field/Li^(+)concentration gradient.The Li^(+) adsorbed by the poly(amic acid)(PAA)insulating layer coated on the anode surface can form the Li^(+)concentration gradient pointing to the center of the hole.Combined with the special electric field formed by the hole structure,it is favorable for the Li^(+)to move into the vertically arrayed holes and simultaneously deposit on the bottom and walls.Furthermore,both in-situ and ex-situ observations confirm that the growth mode is changed and the Li deposition morphology is denser,which can greatly delay capacity fading and prolong cycle life in both liquid and quasi-solid-state LMBs.All the results show that the novel anode provides a new perspective for deep research into solid-state LMBs.

One step hot-pressing method for hybrid Li metal anode of solid-state lithium metal batteries

Safety issues induced by infinite anode volume change and uncontrolled lithium(Li)dendrite growth have become the biggest obstacle to the practical application of Li metal batteries.In addition,the tra-ditional rolling method makes it difficult to manufacture thin Li foil with high mechanical strength and low Li content.Herein,a three-dimensional(3D)lithophilic carbon paper/copper(Cu)current collector hybrid anode with ultra-low Li metal content is prepared by a hot-pressing method.The highly re-versible and stable lithiophilic layer LiC_(x) formed in situ by heating/pressing treatment provides abun-dant nucleation sites and reduces the Li nucleation overpotential,thereby effectively suppressing Li den-drite growth.Moreover,the volume change and pulverization problems of Li metal anode during depo-sition/stripping also can be accommodated by the 3D skeleton.The optimization effect has been directly confirmed by in-situ optical and ex-situ scanning electron microscope observation.Therefore,highly sta-ble performance(158.4 mA h g^(-1) at 2 C after 200 cycles with a capacity retention of 95.24%)in Li@LCP-Cu||NCM811 coin cell can be achieved.Furthermore,the solid-state battery assembled with the hybrid anode,poly(vinylidene fluoride)(PVDF)-based polymer electrolyte and polyethylene oxide(PEO)interface functional layer also exhibits the best electrochemical and safety performance,which also proves that the Li@LCP-Cu anode has great potential for application in solid-state batteries.

Optical haze of transparent and conductive silver nanowire films

Contemporary nanostructured transparent electrodes for use in solar cells require high transmittance and high conductivity, dictating nanostructures with high aspect ratios. Optical haze is an equally important yet unstudied parameter in transparent electrodes for solar cells that is also determined by the geometry of the nanostructures that compose the electrode. In this work, the effect of the silver nanowire diameter on the optical haze values in the visible spectrum was investigated using films composed of wires with either small diameters （N60 nm） or large diameters （~150 nm）. Finite difference time domain （FDTD） simulations and experimental transmittance data confirm that smaller diameter nanowires form higher performing transparent conducting electrode （TCE） films according to the current figure of merit. While maintaining near constant transmittance and conductivity for each film, however, it was observed experimentally that films composed of silver nanowires with larger diameters have a higher haze factor than films with smaller diameters. This confirms the FDTD simulations of the haze factor for single nanowires with similarly large and small diameters. This is the first record of haze properties for Ag NWs that have been simulated or experimentally measured, and also the first evidence that the current figure of merit for TCEs is insufficient to evaluate their performance in solar cell devices.

Ultrathin Al2O3-coated reduced graphene oxide membrane for stable lithium metal anode

Lithium （Li） metal has been considered as the most attractive anode materials for Li-ion batteries （LIBs） due to its high theoretic specific capacity. The formation of unstable solid electrolyte interphase （SEI） and dendritic Li on the metal anode, however, hindered its practical application. Herein, to address the issues, a Li-free electrode with ultrathin Al2O3 coated on reduced graphene oxide （rGO） membrane that covers a Cu foil current collector was developed. The composite electrode exhibits excellent interfacial protection of lithium metal deposited between Cu foil and rGO electrochemically. Firstly, it affords good Li^＋ permeability from the electrolyte. Secondly, the ultrathin Al2O3 has sufficient mechanical strength to inhibit the penetration of Li dendrite. Li metal was observed uniformly deposited between rGO membrane and Cu collector, and stable cycle performance of Li plating/stripping with Coulombic efficiency of ~ 91.75% at the lOOth cycle is achieved in organic carbonate electrolyte without any additives.

Scalable synthesis of sub-lO0 nm hollow carbon nanospheres for energy storage applications

Sub-100 nm hollow carbon nanospheres with thin shells are highly desirable anode materials for energy storage applications. However, their synthesis remains a great challenge with conventional strategies. In this work, we demonstrate that hollow carbon nanospheres of unprecedentedly small sizes （down to - 32.5 nm and with thickness of - 3.9 nm） can be produced on a large scale by a templating process in a unique reverse micelle system. Reverse micelles enable a spatially confined Stober process that produces uniform silica nanospheres with significantly reduced sizes compared with those from a conventional Stober process, and a subsequent well-controlled sol-gel coating process with a resorcinol-formaldehyde resin on these silica nanospheres as a precursor of the hollow carbon nanospheres. Owing to the short diffusion length resulting from their hollow structure, as well as their small size and microporosity, these hollow carbon nanospheres show excellent capacity and cycling stability when used as anode materials for lithium/sodium-ion batteries.

2020 roadmap on two-dimensional materials for energy storage and conversion

Energy storage and conversion have attained significant intere st owing to its important applications that reduce CO2 emission through employing green energy.Some promising technologies are included metalair batteries,metal-sulfur batteries,metal-ion batteries,electrochemical capacitors,etc.Here,metal elements are involved with lithium,sodium,and magnesium.For these devices,electrode materials are of importance to obtain high performance.Two-dimensional(2 D) materials are a large kind of layered structured materials with promising future as energy storage materials,which include graphene,black phosporu s,MXenes,covalent organic frameworks(COFs),2 D oxides,2 D chalcogenides,and others.Great progress has been achieved to go ahead for 2 D materials in energy storage and conversion.More researchers will join in this research field.Under the background,it has motivated us to contribute with a roadmap on ’two-dimensional materials for energy storage and conversion.

Hunting Sodium Dendrites in NASICON-BasedSolid-State Electrolytes

NASICON-(Na superionic conductor-)based solid-state electrolytes(SSEs)are believed to be attracting candidates for solid-state sodium batteries due to their high ionic conductivity and prospectively reliable stability.However,the poor interface compatibility and the formation of Na dendrites inhibit their practical application.Herein,we directly observed the propagation of Na dendrites through NASICON-based Na3.1Zr2Si2.1P0.9O12 SSE for the first time.Moreover,a fluorinated amorphous carbon(FAC)interfacial layer on the ceramic surface was simply developed by in situ carbonization of PVDF to improve the compatibility between Na metal and SSEs.Surprisingly,Na dendrites were effectively suppressed due to the formation of NaF in the interface when molten Na metal contacts with the FAC layer.Benefiting from the optimized interface,both the Na||Na symmetric cells and Na3V2(PO4)3||Na solidstate sodium batteries deliver remarkably electrochemical stability.These results offer benign reference to the maturation of NASICON-based solid-state sodium batteries.