A Self-Deoxidizing Electrolyte Additive Enables Highly Stable Aqueous Zinc Batteries.

In aqueous zinc (Zn) batteries, the Zn anode suffers from severe corrosion reactions and consequent dendrite growth troubles that cause fast performance decay. Herein, we uncover the corrosion mechanism and confirm that the dissolved oxygen (DO) other than the reputed proton is a principal origin of Zn corrosion and by-product precipitates, especially during the initial battery resting period. In a break from common physical deoxygenation methods, we propose a chemical self-deoxygenation strategy to tackle the DO-induced hazards. As a proof of concept, sodium anthraquinone-2-sulfonate (AQS) is introduced to aqueous electrolytes as a self-deoxidizing additive. As a result, the Zn anode sustains a long-term cycling of 2500 h at 0.5 mA cm-2 and over 1100 h at 5 mA cm-2 together with a high Coulombic efficiency up to 99.6 %. The full cells also show a high capacity retention of 92 % after 500 cycles. Our findings provide a renewed understanding of Zn corrosion in aqueous electrolytes and also a practical solution towards industrializing aqueous Zn batteries.

A Corrosion-Resistant and Dendrite-Free Zinc Metal Anode in Aqueous Systems.

Rechargeable aqueous zinc (Zn) ion-based energy storage systems have been reviving recently because of their low cost and high safety merits; however, they still suffer from the problems of corrosion and dendrite growth on Zn metal anodes that cause gas generation and early battery failure. Unfortunately, the corrosion problem has not received sufficient attention until now. Here, it is pioneeringly demonstrated that decorating the Zn surface with a dual-functional metallic indium (In) layer, acting as both a corrosion inhibitor and a nucleating agent, is a facile but effective strategy to suppress both drastic corrosion and dendrite growth. Symmetric cells assembled with the treated Zn electrodes can sustain up to 1500 h of plating/stripping cycles with an ultralow voltage hysteresis (54 mV), and a 5000 cycle-life is achieved for a prototype full cell. This work will instigate the further development of aqueous metal-based energy storage systems.

Ultrasmall, Amorphous V2O3 Intimately Anchored on a Carbon Nanofiber Aerogel Toward High-Rate Zinc-Ion Batteries.

When considered as a cathode candidate for aqueous Zn-ion batteries, V2O3 faces several problems, such as inherently unsuitable structure, fast structural degradation, and sluggish charge transport kinetics. In this paper, we report the synthesis of a V2O3 intimately coupled carbon aerogel by a controllable ion impregnation and solid-state reaction strategy using bacterial cellulose and ammonium metavanadate as raw materials. In this newly designed structure, the carbonized carbon fiber network provides fast ion and electron transport channels. More importantly, the cellulose aerogel functions as a dispersing and supporting skeleton to realize the particle size reduction, uniform distribution, and amorphous features of V2O3. These advantages work together to realize adequate electrochemical activation during the initial charging process and shorter transport distance and faster transport kinetics of Zn2+. The batteries based on the V2O3/CNF aerogel exhibit a high-rate performance and an excellent cycling stability. At a current density of 20 A g-1, the V2O3/CNF aerogel delivers a specific capacity of 159.8 mAh g-1, and it demonstrates an exceptionally long life span over 2000 cycles at 12 A g-1. Furthermore, the electrodes with active material loadings as high as 10 mg cm-2 still deliver appreciable specific capacities of 257 mAh g-1 at 0.1 A g-1.

Switching Hydrophobic Interface with Ionic Valves for Reversible Zinc Batteries.

Developing hydrophobic interface has proven effective in addressing dendrite growth and side reactions during zinc (Zn) plating in aqueous Zn batteries. However, this solution inadvertently impedes the solvation of Zn2+ with H2O and subsequent ionic transport during Zn stripping, leading to insufficient reversibility. Herein, an adaptive hydrophobic interface that can be switched "on" and "off" by ionic valves to accommodate the varying demands for interfacial H2O during both the Zn plating and stripping processes, is proposed. This concept is validated using octyltrimethyl ammonium bromide (C8TAB) as the ionic valve, which can initiatively establish and remove a hydrophobic interface in response to distinct electric-field directions during Zn plating and stripping, respectively. Consequently, the Zn anode exhibits an extended cycling life of over 2500 h with a high Coulombic efficiency of ≈99.8%. The full cells also show impressive capacity retention of over 85% after 1 000 cycles at 5 A g-1. These findings provide a new insight into interface design for aqueous metal batteries.

Aminosilane Molecular Layer Enables Successive Capture-Diffusion-Deposition of Ions toward Reversible Zinc Electrochemistry.

The aqueous zinc (Zn) battery is a safe and eco-friendly energy-storage system. However, the use of Zn metal anodes is impeded by uncontrolled Zn deposition behavior. Herein, we regulate the Zn-ion deposition process for dendrite-free Zn metal anodes using an aminosilane molecular layer with high zincophilic sites and narrow molecule channels. The aminosilane molecular layer causes Zn ions to undergo consecutive processes including being captured by the amine functional groups of aminosilane and diffusing through narrow intermolecular channels before electroplating, which induces partial dehydration of hydrated Zn ions and uniform Zn ion flux, promoting reversible Zn stripping/plating. Through this molecule-induced capture-diffusion-deposition procedure of Zn ions, smooth and compact Zn electrodeposited layers are obtained. Hence, the aminosilane-modified Zn anode has high Coulombic efficiency (∼99.5%), long lifespan (∼3000 h), and high capacity retention in full cells (88.4% for 600 cycles). This strategy not only has great potential for achieving dendrite-free Zn anodes in practical Zn batteries but also suggests an interface-modification principle at the molecular level for other alternative metallic anodes.

Steering surface reconstruction of copper with electrolyte additives for CO2 electroreduction.

Electrocatalytic CO2 reduction to value-added hydrocarbon products using metallic copper (Cu) catalysts is a potentially sustainable approach to facilitate carbon neutrality. However, Cu metal suffers from unavoidable and uncontrollable surface reconstruction during electrocatalysis, which can have either adverse or beneficial effects on its electrocatalytic performance. In a break from the current catalyst design path, we propose a strategy guiding the reconstruction process in a favorable direction to improve the performance. Typically, the controlled surface reconstruction is facilely realized using an electrolyte additive, ethylenediamine tetramethylenephosphonic acid, to substantially promote CO2 electroreduction to CH4 for commercial polycrystalline Cu. As a result, a stable CH4 Faradaic efficiency of 64% with a partial current density of 192 mA cm-2, thus enabling an impressive CO2-to-CH4 conversion rate of 0.25 µmol cm-2 s-1, is achieved in an alkaline flow cell. We believe our study will promote the exploration of electrochemical reconstruction and provide a promising route for the discovery of high-performance electrocatalysts.

A template oriented one-dimensional Schiff-base polymer: towards flexible nitrogen-enriched carbonaceous electrodes with ultrahigh electrochemical capacity.

Lithium-ion capacitors (LICs) have attracted much attention considering their efficient combination of high energy density and high-power density. However, to meet the increasing requirements of energy storage devices and the flexible portable electronic equipment, it is still challenging to develop flexible LIC anodes with high specific capacity and excellent rate capability. Herein, we propose a delicate bottom-up strategy to integrate unique Schiff-base-type polymers into desirable one-dimensional (1D) polymeric structures. A secondary-polymerization-induced template-oriented synthesis approach realizes the 1D integration of Schiff-base porous organic polymers with appealing characteristics of a high nitrogen-doping level and developed pore channels, and a further thermalization yields flexible nitrogen-enriched carbon nanofibers with high specific capacity and fast ion transport. Remarkably, when used as the flexible anode in LICs, the NPCNF//AC LIC demonstrates a high energy density of 154 W h kg-1 at 500 W kg-1 and a high power density of 12.5 kW kg-1 at 104 W h kg-1. This work may provide a new scenario for synthesizing 1D Schiff-base-type polymer derived nitrogen-enriched carbonaceous materials towards promising free-standing anodes in LICs.

Packing Activated Carbons into Dense Graphene Network by Capillarity for High Volumetric Performance Supercapacitors.

Supercapacitors are increasingly in demand among energy storage devices. Due to their abundant porosity and low cost, activated carbons are the most promising electrode materials and have been commercialized in supercapacitors for many years. However, their low packing density leads to an unsatisfactory volumetric performance, which is a big obstacle for their practical use where a high volumetric energy density is necessary. Inspired by the dense structure of irregular pomegranate grains, a simple yet effective approach to pack activated carbons into a compact graphene network with graphene as the "peels" is reported here. The capillary shrinkage of the graphene network sharply reduces the voids between the activated carbon particles through the microcosmic rearrangement while retaining their inner porosity. As a result, the electrode density increases from 0.41 to 0.76 g cm-3. When used as additive-free electrodes for supercapacitors in an ionic liquid electrolyte, this porous yet dense electrode delivers a volumetric capacitance of up to 138 F cm-3, achieving high gravimetric and volumetric energy densities of 101 Wh kg-1 and 77 Wh L-1, respectively. Such a graphene-assisted densification strategy can be extended to the densification of other carbon or noncarbon particles for energy devices requiring a high volumetric performance.

Fast Gelation of Ti3 C2 Tx MXene Initiated by Metal Ions.

Gelation is an effective way to realize the self-assembly of nanomaterials into different macrostructures, and in a typical use, the gelation of graphene oxide (GO) produces various graphene-based carbon materials with different applications. However, the gelation of MXenes, another important type of 2D materials that have different surface chemistry from GO, is difficult to achieve. Here, the first gelation of MXenes in an aqueous dispersion that is initiated by divalent metal ions is reported, where the strong interaction between these ions and OH groups on the MXene surface plays a key role. Typically, Fe2+ ions are introduced in the MXene dispersion which destroys the electrostatic repulsion force between the MXene nanosheets in the dispersion and acts as linkers to bond the nanosheets together, forming a 3D MXene network. The obtained hydrogel effectively avoids the restacking of the MXene nanosheets and greatly improves their surface utilization, resulting in a high rate performance when used as a supercapacitor electrode (≈226 F g-1 at 1 V s-1 ). It is believed that the gelation of MXenes indicates a new way to build various tunable MXene-based structures and develop different applications.

Caging tin oxide in three-dimensional graphene networks for superior volumetric lithium storage.

Tin and its compounds hold promise for the development of high-capacity anode materials that could replace graphitic carbon used in current lithium-ion batteries. However, the introduced porosity in current electrode designs to buffer the volume changes of active materials during cycling does not afford high volumetric performance. Here, we show a strategy leveraging a sulfur sacrificial agent for controlled utility of void space in a tin oxide/graphene composite anode. In a typical synthesis using the capillary drying of graphene hydrogels, sulfur is employed with hard tin oxide nanoparticles inside the contraction hydrogels. The resultant graphene-caged tin oxide delivers an ultrahigh volumetric capacity of 2123 mAh cm-3 together with good cycling stability. Our results suggest not only a conversion-type composite anode that allows for good electrochemical characteristics, but also a general synthetic means to engineering the packing density of graphene nanosheets for high energy storage capabilities in small volumes.

[Dose-effect relationship of DMSO and Tween 80 influencing the growth and viability of murine bone marrow-derived cells in vitro].

This study was purpose to examine the effect of dimethyl sulfoxide (DMSO) and Tween 80 on the growth and viability of stromal cells (BMSC), colony-forming units for granulocytes and macrophages (CFU-GM) and bone marrow endothelial cell line (BMEC) from murine bone marrow in vitro, and to analyze the concentration-effect relationship. The colony yields of colony-forming units fibroblastic (CFU-F) and CFU-GM were assessed in the murine bone marrow cell cultures at various concentrations of DMSO or Tween 80 and in the control groups. The MTT assay and trypan blue exclusion were used to determine the cell viability and percentage of survival in BMSC and BMEC cultures with or without either of these organic solvents. The results showed that the colony yields of both CFU-F and CFU-GM were decreased significantly (p<0.05 or <0.01) at the concentrations (v/v final) of 2% DMSO or 0.005%-0.01% Tween 80 respectively, as compared with control. The cell viability and percentage of survival of BMSC and BMEC cultures were significantly reduced (p<0.05 or <0.01) at 0.5%-1.0% DMSO or 0.002%-0.005% Tween 80, as compared with control. With the increase of volume fractions of these solvents, the decreased percentages of corresponding measurements were increased by degrees. It is concluded that when the concentration of DMSO or Tween 80 goes to a certain level in cell culture medium, either of the organic solvents has an inhibitory action or/and cytotoxicity on the growth and viability of BMSCs, CFU-GM and BMECs. The growth inhibition and cytotoxic response are more significant at higher concentrations of these solvents.