Thin Nano Cages with Limited Hollow Space for Ultrahigh Sulfur Loading Lithium-Sulfur Batteries.

Owning to its various advantages, the lithium-sulfur battery is one of the research hot spots for new energy storage systems. Diverse hollow structures with specific morphologies have been used as the sulfur host materials to adsorb or/and catalyze the polysulfides, and can in particular concurrently inhibit the volume expansion during electrochemical processes in lithium-sulfur batteries. However, hollow space with a large volume will restrict the performance of the cell under high sulfur area loading, which is a very important indicator for the practical applications of the lithium-sulfur battery.

Single-dispersed polyoxometalate clusters embedded on multilayer graphene as a bifunctional electrocatalyst for efficient Li-S batteries.

The redox reactions occurring in the Li-S battery positive electrode conceal various and critical electrocatalytic processes, which strongly influence the performances of this electrochemical energy storage system. Here, we report the development of a single-dispersed molecular cluster catalyst composite comprising of a polyoxometalate framework ([Co(PWO)]) and multilayer reduced graphene oxide. Due to the interfacial charge transfer and exposure of unsaturated cobalt sites, the composite demonstrates efficient polysulfides adsorption and reduced activation energy for polysulfides conversion, thus serving as a bifunctional electrocatalyst.

A carbon-based material with a hierarchical structure and intrinsic heteroatom sites for sodium-ion storage with ultrahigh rate and capacity.

The storage of sodium ions with carbon materials has huge potential for large-scale application due to its resource-rich and environmental advantages. However, how to realize high power density, high energy density and long cycle life are the bottlenecks restricting its development. Herein, by using a facile synthesis strategy, a carbon-based framework with a hierarchical structure and intrinsic heteroatom sites which are the characteristics contributing to ultrahigh rate and capacity has been achieved.

A Carbon Foam with Sodiophilic Surface for Highly Reversible, Ultra-Long Cycle Sodium Metal Anode.

Sodium metal anodes combine low redox potential (-2.71 V versus SHE) and high theoretical capacity (1165 mAh g), becoming a promising anode material for sodium-ion batteries. Due to the infinite volume change, unstable SEI films, and Na dendrite growth, it is arduous to achieve a long lifespan.

A Holey Graphene Additive for Boosting Performance of Electric Double-Layer Supercapacitors.

We demonstrate a facile and effective method, which is low-cost and easy to scale up, to fabricate holey graphene nanosheets (HGNSs) via ultrafast heating during synthesis. Various heating temperatures are used to modify the material properties of HGNSs. First, we use HGNSs as the electrode active materials for electric double-layer capacitors (EDLCs).

ZIF-8-Based Quasi-Solid-State Electrolyte for Lithium Batteries.

The quasi-solid-state electrolytes (QSSEs) with an inorganic skeleton, a solid-liquid composite material combining their respective merits, exhibit high ionic conductivity and mechanical strength. However, most quasi-solid electrolytes prepared by immobilizing ionic liquid (IL) or organic liquid electrolyte in inorganic scaffold generally have poor interface compatibility and low lithium ion migration number, which limits its application. Herein, we design and prepare a ZIF-8-based QSSE (ZIF-8 QSSE) in which the ZIF-8 has a special cage structure and interaction with the guest electrolyte to form a composite electrolyte with good ionic conductivity about 1.

Composition Modulation of Ionic Liquid Hybrid Electrolyte for 5 V Lithium-Ion Batteries.

Electrolyte is a key component in high-voltage lithium-ion batteries (LIBs). Bis(trifluoromethanesulfonyl)imide-based ionic liquid (IL)/organic carbonate hybrid electrolytes have been a research focus owing to their excellent balance of safety and ionic conductivity. Nevertheless, corrosion of Al current collectors at high potentials usually happens for this kind of electrolyte.

Tuning Redox Active Polyoxometalates for Efficient Electron-Coupled Proton-Buffer-Mediated Water Splitting.

We present strategies to tune the redox properties of polyoxometalate clusters to enhance the electron-coupled proton-buffer-mediated water splitting process, in which the evolution of hydrogen and oxygen can occur in different forms and is separated in time and space. By substituting the heteroatom template in the Keggin-type polyoxometalate cluster, H ZnW O , it is possible to double the number of electrons and protonation in the redox reactions (from two to four). This increase can be achieved with better matching of the energy levels as indicated by the redox potentials, compared to the ones of well-studied H PW O and H SiW O .

Multifunctional Ion-Sieve Constructed by 2D Materials as an Interlayer for Li-S Batteries.

For Li-S batteries, the interlayer between the separator and sulfur cathode preventing lithium polysulfide (LiPS) travel across the membrane is a research hotspot. The good blocking ability for LiPSs indicates that these interlayers can promote the electrochemistry performance with high S loading. However, most of these interlayers are just used as a simple blocking wall.

Stable Na Plating and Stripping Electrochemistry Promoted by In Situ Construction of an Alloy-Based Sodiophilic Interphase.

Sodium metal anodes are poor due to the reversibility of Na plating/stripping, which hinders their practical applications. A strategy to form a sodiophilic Au-Na alloy interphase on a Cu current collector, involving a sputtered Au thin layer, is shown to enable efficient Na plating/stripping for a certain period of time. Herein, electrochemical behaviors of Na plating on different substrates are explored, and it is revealed that the sodiophilic interphase can be achieved universally by in situ formation of M-Na (M = Au, Sn, and Sb) alloys during Na plating prior to Na bulk deposition in the initial cycle.

Lithiophilic Faceted Cu(100) Surfaces: High Utilization of Host Surface and Cavities for Lithium Metal Anodes.

Lithium metal anodes suffer from poor cycling stability and potential safety hazards. To alleviate these problems, Li thin-film anodes prepared on current collectors (CCs) and Li-free types of anodes that involve direct Li plating on CCs have received increasing attention. In this study, the atomic-scale design of Cu-CC surface lithiophilicity based on surface lattice matching of the bcc Li(110) and fcc Cu(100) faces as well as electrochemical achievement of Cu(100)-preferred surfaces for smooth Li deposition with a low nucleation barrier is reported.

Supercapacitive Properties of Micropore- and Mesopore-Rich Activated Carbon in Ionic-Liquid Electrolytes with Various Constituent Ions.

Ionic-liquid (IL) electrolytes, characterized by large potential windows, intrinsic ionic conductivity, low environmental hazard, and high safety, are used for micropore- and mesopore-rich activated-carbon (AC and AC ) supercapacitors. IL electrolytes consisting of various cations [1-ethyl-3-methylimidazolium (EMI ), N-propyl-N-methylpyrrolidinium (PMP ), and N-butyl-N-methylpyrrolidinium (BMP )] and various anions [bis(trifluoromethylsulfonyl)imide (TFSI ), BF , and bis(fluorosulfonyl)imide (FSI )] are investigated. The electrolyte conductivity, viscosity, and ion transport properties at the AC and AC electrodes are studied.

Designable ultra-smooth ultra-thin solid-electrolyte interphases of three alkali metal anodes.

Dendrite growth of alkali metal anodes limited their lifetime for charge/discharge cycling. Here, we report near-perfect anodes of lithium, sodium, and potassium metals achieved by electrochemical polishing, which removes microscopic defects and creates ultra-smooth ultra-thin solid-electrolyte interphase layers at metal surfaces for providing a homogeneous environment. Precise characterizations by AFM force probing with corroborative in-depth XPS profile analysis reveal that the ultra-smooth ultra-thin solid-electrolyte interphase can be designed to have alternating inorganic-rich and organic-rich/mixed multi-layered structure, which offers mechanical property of coupled rigidity and elasticity.

Strategies to Explore and Develop Reversible Redox Reactions of Li-S in Electrode Architectures Using Silver-Polyoxometalate Clusters.

Investigations of the Ag (I)-substituted Keggin K[HAgPWO] as a bifunctional Lewis acidic and basic catalyst are reported that explore the stabilization of LiS moieties so that reversible redox reactions in S-based electrodes would be possible. Spectroscopic investigations showed that the LiS-moieties can be strongly adsorbed on the {AgPWO} cluster, where the Ag(I) ion can act as a Lewis acid site to further enhance the adsorption of the S-moieties, and these interactions were investigated and rationalized using DFT. These results were used to construct an electrode for use in a Li-S battery with a very high S utilization of 94%, and a coulometric capacity of 1580 mAh g.

Electrolyte Engineering: Optimizing High-Rate Double-Layer Capacitances of Micropore- and Mesopore-Rich Activated Carbon.

Various types of electrolyte cations as well as binary cations are used to optimize the capacitive performance of activated carbon (AC) with different pore structures. The high-rate capability of micropore-rich AC, governed by the mobility of desolvated cations, can outperform that of mesopore-rich AC, which essentially depends on the electrolyte conductivity.

CoN Nanosheet Assembled Mesoporous Sphere as a Matrix for Ultrahigh Sulfur Content Lithium-Sulfur Batteries.

High utilization and loading of sulfur in cathodes holds the key in the realization of Li-S batteries. We here synthesized a CoN mesoporous sphere, which was made up of nanosheets, via an easy and convenient method. This material presents high affinity, speedy trapping, and absorbing capacity for polysulfides and acts as a bifunctional catalysis for sulfur redox processes; therefore it is an ideal matrix for S active material.

High-Performance Polyoxometalate-Based Cathode Materials for Rechargeable Lithium-Ion Batteries.

The polyoxovanadate cluster Li7[V15O36(CO3)] is shown to be an active cathode material in Li-ion batteries, delivering a capacity of 250 mA h g(-1) at 50 mA g(-1) and 140 mA h g(-1) at 10 A g(-1). Li-ion diffusion is rapid in this material and gives rise to an impressive maximum power density output of 25.7 kW kg(-1) (55 kW L(-1)).

An Amorphous Carbon Nitride Composite Derived from ZIF-8 as Anode Material for Sodium-Ion Batteries.

An composite comprising amorphous carbon nitride (ACN) and zinc oxide is derived from ZIF-8 by pyrolysis. The composite is a promising anode material for sodium-ion batteries. The nitrogen content of the ACN composite is as high as 20.

Enhanced electrochemical performance and thermal stability of LiNi(0.5)Mn(1.5)O4 using an electrolyte with sulfolane.

A sulfide-based SEI layer was formed on the surface of a LiNi0.5Mn1.5O4 cathode by using a sulfolane-carbonate mixed solvent electrolyte, which led to an improvement in the electrochemical performance.

Reduced graphene oxide anchoring CoFe2O4 nanoparticles as an effective catalyst for non-aqueous lithium-oxygen batteries.

CoFe2O4 nanoparticles were uniformly anchored on reduced graphene oxide by a facile solvothermal method. The obtained CoFe2O4/reduced graphene oxide (CoFe2O4/rGO) hybrid was employed as catalyst for Li-O2 batteries. It could effectively lower the ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) overpotentials of the batteries and deliver a large capacity of 12 235 mA h grGO(-1) (2116 mA h ghybrid(-1)).

Self-assembly of DNA nanotubes with defined diameters and lengths.

Nanotubes with different sizes can be readily assembled from simple DNA nanomotifs, which consist of just a few unique DNA sequences. Such structurally well-defi ned DNA-nanotubes will have great potential in many technological applications ranging from drug delivery, to determination of biomacromolecular 3D structures, to nanoplasmonic devices.

Precisely controlled resorcinol-formaldehyde resin coating for fabricating core-shell, hollow, and yolk-shell carbon nanostructures.

This work provides a facile one-step sol-gel route to synthesize high-quality resorcinol-formaldehyde (RF) resin coated nanocomposites that can be further used to fabricate desired carbon nanostructures. Colloidal particles with different morphologies and sizes can be coated with high-quality RF resin shells by the proposed cationic surfactant assisted RF resin coating strategy. The as-synthesized RF resin coated nanocomposites are ideal candidates for selective synthesis of core-shell, hollow, and yolk-shell carbon nanostructures.