"Anions-in-Colloid" Hydrated Deep Eutectic Electrolyte for High Reversible Zinc Metal Anodes.

Zn metal suffers from severe zinc dendrites, anion-related side reactions, hydrogen evolution reaction (HER) and narrow electrochemical stable window (ESW). Herein, an"anions-in-colloid" hydrated deep eutectic electrolyte (ACDE-3) is designed to improve the stability of zinc anode. The ACDE-3 reconfigures the hydrogen-bond (HB) network and regulates the solvation shell. More importantly, the hydroxyl-rich ß-cyclodextrins (ß-CDs) in ACDE-3 self-assemble into micelles, in which the steric effect between the adjacent ß-CDs restricts the movement of anions. This unique "anions-in-colloid" structure enables the eutectic system with a high Zn2+ transference number (tZn2+) of 0.84.  Thus, ACDE-3 inhibits the formation of dendrite, prevents the anion-involved side reactions, suppresses the HER, and enlarges the ESW to 2.32 V. The Zn//Zn symmetric cell delivers a long lifespan of 900 hours at 0.5 mAh cm-2, and the Zn//Cu half cells have a high average columbic efficiency (ACE) of 97.9% at 0.5 mAh cm-2 with a uniform and compact zinc deposition. When matched with a poly(1,5-naphthalenediamine) cathode, the full battery with a low negative/positive capacity ratio of 2 can still cycle steadily for 200 cycles at a current density of 1.0 A g-1. Additionally, this electrolyte can operative over a wide temperature range from -40 °C to 40 °C.

Super Hydrous Solvated Structure of Chaotropic Ca2+ Contributes Superior Anti-Freezing Aqueous Electrolytes and Stabilizes the Zn anode.

The further development of aqueous zinc (Zn)-ion batteries (AZIBs) is constrained by the high freezing points and the instability on Zn anodes. Current improvement strategies mainly focus on regulating hydrogen bond (HB) donors (H) of solvent water to disrupt HBs, while neglecting the environment of HB-acceptors (O). Herein, we propose a mechanism of chaotropic cation-regulated HB-acceptor via a "super hydrous solvated" structure. Chaotropic Ca2+ can form a solvated structure via competitively binding O atoms in H2O, effectively breaking the HBs among H2O molecules, thereby reducing the glass transition temperature of hybrid 1 mol L-1 (M) ZnCl2+4 M CaCl2 electrolyte (-113.2 °C). Meanwhile, the high hydratability of Ca2+ contributes to the water-poor solvated structure of Zn2+, suppressing side reactions and uneven Zn deposition. Benefiting from the anti-freezing electrolyte and high reversible Zn anode, the Zn||Pyrene-4,5,9,10-tetraone (PTO) batteries deliver an ultrahigh capacity of 183.9 mAh g-1 at 1.0 A g-1 over 1600-time stable cycling at -60 °C. This work presents a cheap and efficient aqueous electrolyte to simultaneously improve low-temperature performances and Zn stability, broadening the design concepts for antifreeze electrolytes.

Intramolecular Hydrogen Bond Improved Durability and Kinetics for Zinc-Organic Batteries.

Organic compounds have the advantages of green sustainability and high designability, but their high solubility leads to poor durability of zinc-organic batteries. Herein, a high-performance quinone-based polymer (H-PNADBQ) material is designed by introducing an intramolecular hydrogen bonding (HB) strategy. The intramolecular HB (C=O⋯N-H) is formed in the reaction of 1,4-benzoquinone and 1,5-naphthalene diamine, which efficiently reduces the H-PNADBQ solubility and enhances its charge transfer in theory. In situ ultraviolet-visible analysis further reveals the insolubility of H-PNADBQ during the electrochemical cycles, enabling high durability at different current densities. Specifically, the H-PNADBQ electrode with high loading (10 mg cm-2) performs a long cycling life at 125 mA g-1 (> 290 cycles). The H-PNADBQ also shows high rate capability (137.1 mAh g-1 at 25 A g-1) due to significantly improved kinetics inducted by intramolecular HB. This work provides an efficient approach toward insoluble organic electrode materials.

Bifunctional Interphase with Target-Distributed Desolvation Sites and Directionally Depositional Ion Flux for Sustainable Zinc Anode.

Aqueous zinc batteries (AZBs) feature high safety and low cost, but intricate anodic side reactions and dendrite growth severely restrict their commercialization. Herein, ethylenediaminetetraacetic acid (EDTA) grafted metal organic framework (MOF-E) is proposed as a dually-functional anodic interphase for sustainable Zn anode. Specifically, the target-distributed EDTA serves as an ion-trapped tentacle to accelerate the desolvation and ionic transport by powerful chemical coordination, while the MOFs offer suitable ionic channels to induce oriented deposition. As a result, MOF-E interphase fundamentally suppresses side reactions and guides horizontally arranged Zn deposition with (002) preferred orientations. The Zn|MOF-E@Cu cell exhibits a markedly improved Coulombic efficiency of 99.7 % over 2500 cycles, and the MOF-E@Zn|KVOH (KV12 O30-y ⋅ nH2 O) cell yields a steady circulation of 5000 cycles@90.47 % at 8 A g-1 .

Molecular Engineering Design for High-Performance Aqueous Zinc-Organic Battery.

Novel small sulfur heterocyclic quinones (6a,16a-dihydrobenzo[b]naphtho[2',3':5,6][1,4]dithiino[2,3-i]thianthrene-5,7,9,14,16,18-hexaone (4S6Q) and benzo[b]naphtho[2',3':5,6][1,4]dithiino[2,3-i]thianthrene-5,9,14,18-tetraone (4S4Q)) are developed by molecule structural design method and as cathode for aqueous zinc-organic batteries. The conjugated thioether (-S-) bonds as connected units not only improve the conductivity of compounds but also inhibit their dissolution by both extended π-conjugated plane and constructed flexible molecular skeleton. Hence, the Zn//4S6Q and Zn//4S4Q batteries exhibit satisfactory electrochemical performance based on 3.5 mol L-1 (M) Zn(ClO4)2 electrolyte. For instance, the Zn//4S6Q battery obtains 240 and 208.6 mAh g-1 of discharge capacity at 150 mA g-1 and 30 A g-1, respectively. The excellent rate capability is ascribed to the fast reaction kinetics. This system displays a superlong life of 20,000 cycles with no capacity fading at 3 A g-1. Additionally, the H+-storage mechanism of the 4S6Q compound is demonstrated by ex situ analyses and density functional theory calculations. Impressively, the battery can normally work at - 60 °C benefiting from the anti-freezing electrolyte and maintain a high discharge capacity of 201.7 mAh g-1, which is 86.2% of discharge capacity at 25 °C. The cutting-edge electrochemical performances of these novel compounds make them alternative electrode materials for Zn-organic batteries.

Regulating Frozen Electrolyte Structure with Colloidal Dispersion for Low Temperature Aqueous Batteries.

Electrolyte freezing under low temperatures is a critical challenge for the development of aqueous batteries (ABs). While lowering the freezing point of the electrolyte has caught major research efforts, limited attention has been paid to the structural evolution during the electrolyte freezing process and regulating the frozen electrolyte structure for low temperature ABs. Here, we reveal the formation process of interconnected liquid regions for ion transport in frozen electrolytes with various in situ variable-temperature technologies. More importantly, the low-temperature performance of ABs was significantly improved with the colloidal electrolyte design using graphene oxide quantum dots (GOQDs), which effectively inhibits the growth of ice crystals and expands the interconnected liquid regions for facial ion transport. This work provides new insights and a promising strategy for the electrolyte design of low-temperature ABs.

Hydrogen Bond Networks Stabilized High-Capacity Organic Cathode for Lithium-Ion Batteries.

High-capacity small organic materials are plagued by their high solubility. Here we proposed constructing hydrogen bond networks (HBN) via intermolecular hydrogen bonds to suppress the solubility of active material. The illustrated 2, 7- diamino-4, 5, 9, 10-tetraone (PTO-NH2 ) molecule with intermolecular hydrogen (H) bond between O in -C=O and H in -NH2 , which make PTO-NH2 presents transverse two-dimensional extension and longitudinal π-π stacking structure. In situ Fourier transform infrared spectroscopy (FTIR) has tracked the reversible evolution of H-bonds, further confirming the existence of HBN structure can stabilize the intermediate 2-electron reaction state. Therefore, PTO-NH2 with HBN structure has higher active site utilization (95 %), better cycle stability and rate performance. This study uncovers the H-bond effect and evolution during the electrochemical process and provides a strategy for materials design.

Orthoquinone-Based Covalent Organic Frameworks with Ordered Channel Structures for Ultrahigh Performance Aqueous Zinc-Organic Batteries.

Elaborate molecular design on cathodes is of great importance for rechargeable aqueous zinc-organic batteries' performance elevation. Herein, we design a novel orthoquinone-based covalent organic framework with an ordered channel structures (BT-PTO COF) cathode for an ultrahigh performance aqueous zinc-organic battery. The ordered channel structure facilitates ions transfer and makes the COF follow a redox pseudocapacitance mechanism. Thus, it delivers a high reversible capacity of 225 mAh g-1 at 0.1 A g-1 and an exceptional long-term cyclability (retention rate 98.0 % at 5 A g-1 (≈18 C) after 10 000 cycles). Moreover, a co-insertion mechanism with Zn2+ first followed by two H+ is uncovered for the first time. Significantly, this co-insertion behaviour evolves to more H+ insertion routes at high current density and gives the COF ultra-fast kinetics thus it achieves unprecedented specific power of 184 kW kg-1 (COF) and a high energy density of 92.4 Wh kg-1 (COF) . Our work reports a superior organic material for zinc batteries and provides a design idea for future high-performance organic cathodes.

Hydrogen Bond Shielding Effect for High-Performance Aqueous Zinc Ion Batteries.

Manganese oxides are highly desirable for the cathode of rechargeable aqueous zinc ion batteries (AZIBs) owing to their low cost and high abundance. However, the terrible structure stability of manganese oxide limits its practical application. Here, it is demonstrated that the hydrogen-bond shielding effect can improve the electrochemical performance of manganese oxide. Briefly, (NH4 )0.125 MnO2 (NHMO) is prepared by introducing NH4 + into the tunnel structure of α-MnO2 . The robust hydrogen bonds between N-H and host O atoms can stabilize the lattice structure of α-MnO2 and suppress the dissolution of Mn element. More importantly, it can also accelerate ions mobility kinetics by weakening the electrostatic interaction of host O atoms. Thus, the fabricated Zn||NHMO battery possesses impressive cycling life (99.5% of capacity retention over 10 000 cycles) and rate capability (109 mA h g-1 of discharge capacity at 6000 mA g-1 ). Comprehensive analyses reveal the essences of interfacial charge and bulk ions transfer. This finding opens new opportunities for the development of high-performance AZIBs.

Bipolar Organic Polymer for High Performance Symmetric Aqueous Proton Battery.

Bipolar electroactive organic molecules receive an increasing research attention as electrode materials for rechargeable batteries due to their flexibility, controllability, and environmental friendliness. While its application for symmetric aqueous proton batteries is still in its infancy. Herein, a symmetric aqueous proton battery (APB) based on a bipolar poly(aminoanthraquinone) (PNAQ) is developed. The conductivity and solubility of PNAQ are significantly improved by introducing a polyaniline-like skeleton. It is demonstrated that the quinone-based moieties allow H+ reversible uptake/removal and the benzene ring-based units achieve HSO4 - adsorption/desorption. The fabricated symmetric APB exhibits a high discharge capacity of 85.3 mA h g-1 at 5 C and excellent rate performance (77 mA h g-1 at 100 C). The good rate performance benefits from capacitance-like ions diffusion mechanism. Furthermore, surprisingly, the system can also operate at -70 °C and shows superior electrochemical performance (60.4 mA h g-1 at -70 °C).

Synergistic Effect of Cation and Anion for Low-Temperature Aqueous Zinc-Ion Battery.

Although aqueous zinc-ion batteries have gained great development due to their many merits, the frozen aqueous electrolyte hinders their practical application at low temperature conditions. Here, the synergistic effect of cation and anion to break the hydrogen-bonds network of original water molecules is demonstrated by multi-perspective characterization. Then, an aqueous-salt hydrates deep eutectic solvent of 3.5 M Mg(ClO4)2 + 1 M Zn(ClO4)2 is proposed and displays an ultralow freezing point of - 121 °C. A high ionic conductivity of 1.41 mS cm-1 and low viscosity of 22.9 mPa s at - 70 °C imply a fast ions transport behavior of this electrolyte. With the benefits of the low-temperature electrolyte, the fabricated Zn||Pyrene-4,5,9,10-tetraone (PTO) and Zn||Phenazine (PNZ) batteries exhibit satisfactory low-temperature performance. For example, Zn||PTO battery shows a high discharge capacity of 101.5 mAh g-1 at 0.5 C (200 mA g-1) and 71 mAh g-1 at 3 C (1.2 A g-1) when the temperature drops to - 70 °C. This work provides an unique view to design anti-freezing aqueous electrolyte.

Layered Ca0.28 MnO2 ·0.5H2 O as a High Performance Cathode for Aqueous Zinc-Ion Battery.

Aqueous zinc-ion batteries are promising candidates for grid-scale energy storage because of their intrinsic safety, low cost, and high energy intensity. However, lack of suitable cathode materials with both excellent rate performance and cycling stability hinders further practical application of aqueous zinc-ion batteries. Here, a nanoflake-self-assembled nanorod structure of Ca0.28 MnO2 ·0.5H2 O as Zn-insertion cathode material is designed. The Ca0.28 MnO2 ·0.5H2 O exhibits a reversible capacity of 298 mAh g-1 at 175 mA g-1 and long-term cycling stability over 5000 cycles with no obvious capacity fading, which indicates that the per-insertion of Ca ions and water can significantly improve reversible insertion/extraction stability of Zn2+ in Mn-based layered type material. Further, its charge storage mechanism, especially hydrogen ions, is elucidated. A comprehensive study suggests that the intercalation of hydrogen ions in the first discharge plat is controled by both pH value and type of anion of electrolyte. Further, it can stabilize the Ca0.28 MnO2 ·0.5H2 O cathode and facilitate the following insertion of Zn2+ in 1 m ZnSO4 /0.1 m MnSO4 electrolyte. This work can enlighten and promote the development of high-performance rechargeable aqueous zinc-ion batteries.

Aqueous Batteries Operated at -50 °C.

Insufficient ionic conductivity and freezing of the electrolyte are considered the main problems for electrochemical energy storage at low temperatures (low T). Here, an electrolyte with a freezing point lower than -130 °C is developed by using dimethyl sulfoxide (DMSO) as an additive with molar fraction of 0.3 to an aqueous solution of 2 m NaClO4 (2M-0.3 electrolyte). The 2M-0.3 electrolyte exhibits sufficient ionic conductivity of 0.11 mS cm-1 at -50 °C. The combination of spectroscopic investigations and molecular dynamics (MD) simulations reveal that hydrogen bonds are stably formed between DMSO and water molecules, facilitating the operation of the electrolyte at ultra-low T. Using DMSO as the electrolyte additive, the aqueous rechargeable alkali-ion batteries (AABs) can work well even at -50 °C. This work provides a simple and effective strategy to develop low T AABs.

Pharmacokinetics of forsythoside after intravenous administration in beagle dogs.

A high-performance liquid chromatography with ultraviolet detection method was established and validated for quantification of forsythoside concentrations in dog plasma. Following a single-step protein precipitation with perchloric acid, the forsythoside and internal standard were separated on a reversed-phase C18 column with water-glacial acetic acid-methanol as mobile phase at a flow rate of 1 mL/min with ultraviolet detection at 326 and 278 nm for forsythoside and IS, respectively. The calibration curve for forsythoside was linear over a range of 0.052-13.33 microg/mL with correlation coefficient of 0.999. The within- and between-batch precisions of analysis were < 8 % and accuracy was 95-107%. After intravenous administration of forsythoside at the doses of 5, 10, and 20 mg/kg, the C(max) values for forsythoside were estimated to be of 12.33, 22.90 and 54.45 microg/mL, respectively. The AUC increased with the increasing of doses, and the mean AUC(o-t) values were 5.69, 11.80, and 18.66 mg x h/L, respectively. Forsythoside was eliminated quickly and the mean T(1/2) values at doses of 5, 10, and 20 mg/kg were 1.36, 1.49, and 0.71 h, respectively. The pharmacokinetics of forsythoside in beagle dogs complied with linear kinetic course in the dose range.