High Zn2 Research Articles

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

Zn metal as a promising anode for aqueous batteries 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 consisting of Zn(ClO4)2 ⋅ 6H2O, β-cyclodextrin (β-CD), and H2O with mass ratio of 7 : 4.5 : 3 (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 β-cyclodextrins (β-CDs) in ACDE-3 self-assemble into micelles, in which the steric effect between adjacent β-CDs in micelles restricts the movement of anions. This unique "anions-in-colloid" structure enables the eutectic system with a high Zn2+ transference number (tZn 2+) 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 mA cm-2, and the Zn//Cu half cells have a high average columbic efficiency (ACE) of 97.9 % at 0.5 mA cm-2 from cycle 15 to 200 with a uniform and compact zinc deposition. When matched with a poly(1,5-naphthalenediamine) (poly(1, 5-NAPD)) cathode, the full battery with a low negative/positive capacity (N/P) ratio of 2 can still cycle steadily for 200 cycles at a current density of 1.0 A g-1. Additionally, this electrolyte has been proven to be operative over a wide temperature range from -40 °C to 40 °C.

Spatially Confined Engineering Toward Deep Eutectic Electrolyte in Metal-Organic Framework Enabling Solid-State Zinc-Ion Batteries.

Uncontrollable interfacial side reactions generated from common aqueous electrolytes, just like the hydrogen evolution reaction (HER) and dendrite growth, have severely prevented the practical application of zinc-ion batteries (ZIBs). Solid-state ZIBs are considered to be an efficient strategy by adopting high-quality solid-state electrolytes (SSEs). Here, by confining deep eutectic electrolyte (DEE) into the nanochannels of metal-organic framework (MOF)-PCN-222, a stable DEE@PCN-222 SSE with internal Zn2+ transport channels was obtained. A distinctive ion-transport network composed of DEE and PCN-222 in the interior of DEE@PCN-222 realizes the efficient Zn2+ conduction, contributing to high ionic conductivity of 3.13×10-4 S cm-1 at room temperature, low activation energy of 0.12 eV, and a high Zn2+ transference number of 0.74. Furthermore, experimental and theoretical investigations demonstrate that DEE@PCN-222 with its unique channel structure could homogeneously regulate the Zn2+ distribution and effectively alleviate the side reactions. Highly reversible Zn plating/stripping performance of 2476 h can be realized by the SSE. The solid-state ZIBs show a specific capacity of 306 mAh g-1 and display cycling stability of 517 cycles. This unique design concept provides a new perspective in realizing the high-safety and high-performance ZIBs.

Weakening the Space Charge Layer Effect Through Tethered Anion Electrolyte and Piezoelectric Effect Toward Ultra-Stable Zinc Anode.

The space charge layer (SCL) dilemma, caused by mobile anion concentration gradient and the rapid consumption of cations, is the fundamental reason for the generation of zinc dendrites, especially under high-rate discharge conditions. To address the issue, a physical (PbTiO3)/chemical (AMPS-Zn) barrier is designed to construct stable zinc ion flow and disrupt the gradient of anion concentration by coupling the ferroelectric effect with tethered anion electrolyte. The ferroelectric materials PbTiO3 with extreme-high piezoelectric constant can spontaneously generate an internal electric field to accelerate the movement of zinc ions, and the polyanionic polymer AMPS-Zn can repel mobile anions and disrupt the anions concentration gradient by tethering anions. Through numerical simulations and analyses, it is discovered that a high Zn2+ transference number can effectively weaken the SCL, thus suppressing the occurrence of zinc dendrites and parasitic side reactions. Consequently, an asymmetric cell using the PbTiO3@Zn demonstrates a reversible plating/stripping performance for 2900h, and an asymmetric cell reaches a state-of-the-art runtime of 3450h with a high average Coulombic efficiency of 99.98%. Furthermore, the PbTiO3@Zn/I2 battery demonstrated an impressive capacity retention rate of 84.0% over 65000 cycles by employing a slender Zn anode.

Metal-Phosphonate-Organic Network as Ion Enrichment Layer for Sustainable Zinc Metal Electrode with High Rate Capability.

Zinc (Zn) metal batteries could be the technology of choice for sustainable battery chemistries owing to its better safety and cost advantage. However, their cycle life and Coulombic efficiency (CE) are strongly limited by the dendritic growth and side reactions of Zn anodes. Herein, we proposed an in situ construction of a metal-phosphonate-organic network (MPON) with three-dimensional interconnected networks on Zn metal, which can act as an ion enrichment layer for Zn anodes in Zn-metal batteries. This MPON with abundant porous structure and phosphate sites possesses ion enriching properties and high Zn2+ transference number (0.83), which is beneficial for enhancing Zn2+ migration and self-concentrating kinetics. Meanwhile, MPON offers hydrophobicity to effectively inhibit the water-induced Zn anode corrosion. As a result, the Zn electrode exhibits superior Zn/Zn2+ reversibility of over 4 months at 3 mA cm-2 and a high CE of 99.6%. Moreover, the Zn/NaV3O8 ·1.5H2O and Zn/MnO2 full cells using ultrathin Zn anodes (10 μm) exhibit high-capacity retention of 81% and 78% after 1400 and 1000 cycles, respectively. This work provides a unique promise to design high-performance anode for practical Zn-metal-based batteries.

Metal‐Phosphonate‐Organic Network as Ion Enrichment Layer for Sustainable Zinc Metal Electrode with High Rate Capability

Zinc (Zn) metal batteries could be the technology of choice for sustainable battery chemistries owing to its better safety and cost advantage. However, their cycle life and Coulombic efficiency (CE) are strongly limited by the dendritic growth and side reactions of Zn anodes. Herein, we proposed an in situ construction of a metal−phosphonate−organic network (MPON) with three−dimensional interconnected networks on Zn metal, which can act as an ion enrichment layer for Zn anodes in Zn‐metal batteries. This MPON with abundant porous structure and phosphate sites possesses ion enriching properties and high Zn2+ transference number (0.83), which is beneficial for enhancing Zn2+ migration and self−concentrating kinetics. Meanwhile, MPON offers hydrophobicity to effectively inhibit the water−induced Zn anode corrosion. As a result, the Zn electrode exhibits superior Zn/Zn2+ reversibility of over 4 months at 3 mA cm−2 and a high CE of 99.6%. Moreover, the Zn/NaV3O8 ·1.5H2O and Zn/MnO2 full cells using ultrathin Zn anodes (10 μm) exhibit high−capacity retention of 81% and 78% after 1400 and 1000 cycles, respectively. This work provides a unique promise to design high−performance anode for practical Zn−metal−based batteries.

A Synergistically Regulated Cathode/Electrolyte Interphase With High Stability and Rapid Zn2+ Migration Toward Advanced Flexible Zinc-Ion Batteries.

Na3V2(PO4)3(NVP), as a representative sodium superionic conductor with a stable polyanion framework, is considered a cathode candidate for aqueous zinc-ion batteries attributed to their high discharge platform and open 3D structure. Nevertheless, the structural stability of NVP and the cathode-electrolyte interphase (CEI) layer formed on NVP can be deteriorated by the aqueous electrolyte to a certain extent, which will result in slow Zn2+ migration. To solve these problems, doping Si elements to NVP and adding sodium acetate (NaAc) to the electrolyte are utilized as a synergistic regulation route to enable a highly stable CEI with rapid Zn2+ migration. In this regard, Ac- competitively takes part in the solvation structure of Zn2+ in aqueous electrolyte, weakening the interaction between water and Zn2+, and meanwhile a highly stable CEI is formed to avoid structural damage and enable rapid Zn2+ migration. The NVPS/C@rGO electrode exhibits a notable capacity of 115.5mAhg-1 at a current density of 50mAg-1 in the mixed electrolyte (3M ZnOTF2+3M NaAc). Eventually, a collapsible "sandwich" soft pack battery is designed and fabricated and can be used to power small fans and LEDs, which proves the practical application of aqueous zinc-ion batteries in flexible batteries.

Simultaneous Inhibition of Vanadium Dissolution and Zinc Dendrites by Mineral‐Derived Solid‐State Electrolyte for High‐Performance Zinc Metal Batteries

Designing solid electrolyte is deemed as an effective approach to suppress the side reaction of zinc anode and active material dissolution of cathodes in liquid electrolytes for zinc metal batteries (ZMBs). Herein, kaolin is comprehensively investigated as raw material to prepare solid electrolyte (KL‐Zn) for ZMBs. As demonstrated, KL‐Zn electrolyte is an excellent electronic insulator and zinc ionic conductor, which presents wide voltage window of 2.73 V, high ionic conductivity of 5.08 mS cm‐1, and high Zn2+ transference number of 0.79. For the Zn//Zn cells, superior cyclic stability lasting for 2200 h can be achieved at 0.2 mA cm‐2. For the Zn//NH4V4O10 batteries, stable capacity of 245.8 mAh g‐1 can be maintained at 0.2 A g‐1 after 200 cycles along with high retention ratio of 81%, manifesting KL‐Zn electrolyte contributes to stabilize the crystal structure of NH4V4O10 cathode. These satisfying performances can be attributed to the enlarged interlayer spacing, zinc (de)solvation‐free mechanism and fast diffusion kinetics of KL‐Zn electrolyte, availably guaranteeing uniform zinc deposition for zinc anode and reversible zinc (de)intercalation for NH4V4O10 cathode. Additionally, this work also verifies the application possibility of KL‐Zn electrolyte for Zn//MnO2 batteries and Zn//I2 batteries, suggesting the universality of mineral‐based solid electrolyte.

Simultaneous Inhibition of Vanadium Dissolution and Zinc Dendrites by Mineral-Derived Solid-State Electrolyte for High-Performance Zinc Metal Batteries.

Designing solid electrolyte is deemed as an effective approach to suppress the side reaction of zinc anode and active material dissolution of cathodes in liquid electrolytes for zinc metal batteries (ZMBs). Herein, kaolin is comprehensively investigated as raw material to prepare solid electrolyte (KL-Zn) for ZMBs. As demonstrated, KL-Zn electrolyte is an excellent electronic insulator and zinc ionic conductor, which presents wide voltage window of 2.73 V, high ionic conductivity of 5.08 mS cm-1, and high Zn2+ transference number of 0.79. For the Zn//Zn cells, superior cyclic stability lasting for 2200 h can be achieved at 0.2 mA cm-2. For the Zn//NH4V4O10 batteries, stable capacity of 245.8 mAh g-1 can be maintained at 0.2 A g-1 after 200 cycles along with high retention ratio of 81%, manifesting KL-Zn electrolyte contributes to stabilize the crystal structure of NH4V4O10 cathode. These satisfying performances can be attributed to the enlarged interlayer spacing, zinc (de)solvation-free mechanism and fast diffusion kinetics of KL-Zn electrolyte, availably guaranteeing uniform zinc deposition for zinc anode and reversible zinc (de)intercalation for NH4V4O10 cathode. Additionally, this work also verifies the application possibility of KL-Zn electrolyte for Zn//MnO2 batteries and Zn//I2 batteries, suggesting the universality of mineral-based solid electrolyte.

Highly reversible Zn anodes enabled by in-situ construction of zincophilic zinc polyacrylate interphase for aqueous Zn-ion batteries

The irreversibility and low utilization of Zn anode stemming from the corrosion and dendrite growth have largely limited the commercialization of aqueous zinc batteries. Here, a carbonyl-rich polymer interphase of zinc polyacrylate (ZPAA) is spontaneously in-situ constructed on Zn anode to address the above-mentioned dilemmas. The ZPAA interlayer enables fast transport kinetics of Zn2+ and tailors the interfacial electric field for realizing the uniform Zn deposition due to superior zincophilicity, high Zn2+ transference number and inherent ion-diffusion channel. Importantly, acting as a buffer interphase with strong adhesion and isolation of electrolytes, this functional layer effectively protects the Zn electrode against the water-induced erosion and passivation. Remarkably, the ZPAA@Zn electrode realizes an enhanced Coulombic efficiency of 99.71 % within 2200 cycles, delivers an ultra-long cycling stability over 7660 h (>319 days, 1 mA cm−2) and 2460 h (5 mA cm−2) with lower voltage hysteresis. Also, the ZPAA@Zn/MnO2 full cell maintains a high capacity of 114 mAh/g after 2000 cycles, much better that of untreated Zn/MnO2 cell (25 mAh/g). This concept of in-situ fabricating ion-sieve-like polymer interphase provides a facile approach to stabilize Zn anode and further paves a way for high-performance aqueous batteries.

Spatially Confined Engineering Toward Deep Eutectic Electrolyte in Metal‐Organic Framework Enabling Solid‐State Zinc‐Ion Batteries

AbstractUncontrollable interfacial side reactions generated from common aqueous electrolytes, just like the hydrogen evolution reaction (HER) and dendrite growth, have severely prevented the practical application of zinc‐ion batteries (ZIBs). Solid‐state ZIBs are considered to be an efficient strategy by adopting high‐quality solid‐state electrolytes (SSEs). Here, by confining deep eutectic electrolyte (DEE) into the nanochannels of metal‐organic framework (MOF)‐PCN‐222, a stable DEE@PCN‐222 SSE with internal Zn2+ transport channels was obtained. A distinctive ion‐transport network composed of DEE and PCN‐222 in the interior of DEE@PCN‐222 realizes the efficient Zn2+ conduction, contributing to high ionic conductivity of 3.13×10−4 S cm−1 at room temperature, low activation energy of 0.12 eV, and a high Zn2+ transference number of 0.74. Furthermore, experimental and theoretical investigations demonstrate that DEE@PCN‐222 with its unique channel structure could homogeneously regulate the Zn2+ distribution and effectively alleviate the side reactions. Highly reversible Zn plating/stripping performance of 2476 h can be realized by the SSE. The solid‐state ZIBs show a specific capacity of 306 mAh g−1 and display cycling stability of 517 cycles. This unique design concept provides a new perspective in realizing the high‐safety and high‐performance ZIBs.

An Ion-Pumping Quasi-Solid Electrolyte Enabled by Electrokinetic Effects for Stable Aqueous Zinc Metal Batteries.

The practical application of aqueous zinc (Zn) metal batteries (ZMBs) is hindered by the complicated hydrogen evolution, passivation reactions, and dendrite growth of Zn metal anodes. Here, an ion-pumping quasi-solid electrolyte (IPQSE) with high Zn2+ transport kinetics enabled by the electrokinetic phenomena to realize high-performance quasi-solid state Zn metal batteries (QSSZMBs) is reported. The IPQSE is prepared through the in situ ring-opening polymerization of tetramethylolmethane-tri-β-aziridinylpropionate in the aqueous electrolyte. The porous polymer framework with high zeta potential provides the IPQSE with an electrokinetic ion-pumping feature enabled by the electrokinetic effects (electro-osmosis and electrokinetic surface conduction), which significantly accelerates the Zn2+ transport, reduces the concentration polarization and overcomes the diffusion-limited current. Moreover, the Zn2+ affinity of the polymer and hydrogen bonding interactions in the IPQSE changes the Zn2+ coordination environment and reduces the amount of free H2O, which lowers the H2O activity and inhibits H2O-induced side reactions. Consequently, the highly reversible and stable Zn metal anodes are achieved. The assembled QSSZMBs based on the IPQSE display excellent cycling stability with high capacity retention and Coulombic efficiency. The high-performance quasi-solid state Zn metal pouch cells are demonstrated, showing great promise for the practical application of the IPQSE.

Zinc inhibits the voltage-gated proton channel HCNL1

Voltage-gated ion channels allow ion flux across biological membranes in response to changes in the membrane potential. HCNL1 is a recently discovered voltage-gated ion channel that selectively conducts protons through its voltage-sensing domain (VSD), reminiscent of the well-studied depolarization-activated Hv1 proton channel. However, HCNL1 is activated by hyperpolarization, allowing the influx of protons, which leads to an intracellular acidification in zebrafish sperm. Zinc ions (Zn2+) are important cofactors in many proteins and essential for sperm physiology. Proton channels such as Hv1 and Otopetrin1 are inhibited by Zn2+. We investigated the effect of Zn2+ on heterologously expressed HCNL1 channels using electrophysiological and fluorometric techniques. Extracellular Zn2+ inhibits HCNL1 currents with an apparent half-maximal inhibition (IC50) of 26 μM. Zn2+ slows voltage-dependent current kinetics, shifts the voltage-dependent activation to more negative potentials, and alters hyperpolarization-induced conformational changes of the voltage sensor. Our data suggest that extracellular Zn2+ inhibits HCNL1 currents by multiple mechanisms, including modulation of channel gating. Two histidine residues located at the extracellular side of the VSD might weakly contribute to Zn2+ coordination: mutants with either histidine replaced with alanine show modest shifts of the IC50 values to higher concentrations. Interestingly, Zn2+ inhibits HCNL1 at even lower concentrations from the intracellular side (IC50 ≈ 0.5 μM). A histidine residue at the intracellular end of S1 (position 50) is important for Zn2+ binding: much higher Zn2+ concentrations are required to inhibit the mutant HCNL1-H50A (IC50 ≈ 106 μM). We anticipate that Zn2+ will be a useful ion to study the structure-function relationship of HCNL1 as well as the physiological role of HCNL1 in zebrafish sperm.

Constructing Gradient Separator to Stabilize Bi‐electrodes Toward High‐Performance Zn Metal Batteries

AbstractAqueous zinc (Zn) metal batteries have considerable potential as large‐scale energy storage systems. However, cathodic metal ions dissolution and anodic dendrite growth constrain their further development. Here, an ion gradient separator is proposed to stabilize the bi‐electrodes of Zn metal batteries. The results show that the constructed low Zn2+ concentration region in the separator helps the NH4V4O10 (NVO) model cathode to maintain good electrolyte wettability and form a N/ZnS/ZnF2‐rich cathode‐electrolyte interphase (CEI), exhibiting a low vanadium (V) dissolution behavior. Meanwhile, the high Zn2+ concentration region in the separator and the flexible solid electrolyte interphase (SEI) inhibit the dendrite growth and parasitic reactions of the Zn metal anode and further prevent the diffusion of V ions. As a proof‐of‐concept, the NVO||Zn battery with gradient separator can achieve 88.1% capacity retention even after cycling over 800 cycles at 1 A g−1, while the ordinary separator only maintains 14.8%. This work presents an innovative gradient separator strategy for achieving high‐performance Zn metal batteries and sheds light on other rechargeable batteries.

Mullite Mineral-Derived Robust Solid Electrolyte Enables Polyiodide Shuttle-Free Zinc-Iodine Batteries.

Zinc dendrite, active iodine dissolution, and polyiodide shuttle caused by the strong interaction between liquid electrolyte and solid electrode are the chief culprits for the capacity attenuation of aqueous zinc-iodine batteries (ZIBs). Herein, mullite is adopted as raw material to prepare Zn-based solid-state electrolyte (Zn-ML) for ZIBs through zinc ion exchange strategy. Owing to the merits of low electronic conductivity, low zinc diffusion energy barrier, and strong polyiodide adsorption capability, Zn-ML electrolyte can effectively isolate the redox reactions of zinc anode and AC@I2 cathode, guide the reversible zinc deposition behavior, and inhibit the active iodine dissolution as well as polyiodide shuttle during cycling process. As expected, wide operating voltage window of 2.7V (vs Zn2+/Zn), high Zn2+ transference number of 0.51, and low activation energy barrier of 29.7kJ mol-1 can be achieved for the solid-state Zn//Zn cells. Meanwhile, high reversible capacity of 127.4 and 107.6 mAh g-1 can be maintained at 0.5 and 1 A g-1 after 3000 and 2100 cycles for the solid-state Zn//AC@I2 batteries, corresponding to high-capacity retention ratio of 85.2% and 80.7%, respectively. This study will inspire the development of mineral-derived solid electrolyte, and facilitate its application in Zn-based secondary batteries.

Reconstruction of zinc-metal battery solvation structures operating from −50 ~ +100 °C

Serious solvation effect of zinc ions has been considered as the cause of the severe side reactions (hydrogen evolution, passivation, dendrites, and etc.) of aqueous zinc metal batteries. Even though the regulation of cationic solvation structure has been widely studied, effects of the anionic solvation structures on the zinc metal were rarely examined. Herein, co-reconstruction of anionic and cationic solvation structures was realized through constructing a new multi-component electrolyte (Zn(BF4)2-glycerol-boric acid-chitosan-polyacrylamide, simplified as ZGBCP), which incorporates double crosslinking network via the esterification, protonation and polymerization reactions, thereby combining multiple advantages of ‘liquid-like’ high conductivity, ‘gel-like’ robust interface, and ‘solid-like’ high Zn2+ transfer number. Based on the ZGBCP electrolyte, the Zn anodes achieve record-low polarization and stable cycling. Furthermore, the ZGBCP electrolyte renders the AZMBs ultrawide working temperature (−50 °C ~ +100 °C) and ultralong cycle life (30000 cycles), which further validates the feasibility of the dual solvation structure strategy and provides a innovative perspective for the development of high-performance AZMBs.

Construction of an n-Type Fluorinated ZnO Interfacial Phase for a Stable Anode of Aqueous Zinc-Ion Batteries.

Aqueous rechargeable zinc-ion batteries have become an ideal solution for the next generation of energy storage systems due to their low cost and high safety. However, the uncontrollable zinc dendrites and harmful side reactions of metal zinc anodes hinder the further development of aqueous zinc-ion batteries. In this work, the artificial fluoride zinc oxide (F-ZnO) interface phase is integrated in situ on the surface of zinc foil. The F-ZnO interface phase significantly inhibits the side reactions on the surface of the zinc electrode by reducing the direct contact between the electrolyte and the surface of the zinc foil. In addition, F-ZnO modified by a small amount of F doping shows enhanced conductivity and electron transport capacity, avoiding the accumulation of high concentration Zn2+ on the anode surface, and ultimately promoting the efficient nucleation and orderly deposition of a zinc anode. The cycle life of the symmetrical cell based on F-ZnO is as high as 2600 cycles at an area current density of 4 mA cm-2, which is much better than that of a commercial pure Zn electrode. The modified F-ZnO@Zn anode truly achieves the purpose of prolonging the anode's life.

In Situ Assembly of Metal‐Organic Coordination Polymer Layers Enables Highly Reversible Zn Anodes with a Long Cycle Life of over 6900 h

AbstractZn anodes in aqueous zinc‐ion batteries chronically suffer from pernicious side reactions and ineluctable dendrite growth, resulting in inadequate reversibility and suboptimal Coulombic efficiency (CE) and impeding commercialization. Herein, a multifunctional metal–organic coordination polymer layer (FAZ) is constructed on the zinc anode surface (FAZ@Zn) utilizing a simple self‐assembly strategy. The zincophilic FAZ interfacial layer with a high Zn2+ transfer number and low nucleation barrier effectively facilitates the de‐solvation process, supports the rapid transport of zinc ions, and contributes to the preferential growth of Zn (002) crystal planes, enabling dendrite‐free Zn deposition. Furthermore, the FAZ layer, as an interfacial pH regulating layer, effectively inhibits the direct contact between Zn and active water molecules, lowering the severity of side reactions. Consequently, the FAZ@Zn anode furnishes an eminent cycle stability over 6900 h, with a low polarization voltage at 1 mA cm−2 and 1 mA h cm−2 and a boosted CE of 99.88% over 4100 cycles. More encouragingly, when coupled with Na2V6O16·3H2O, the FAZ@Zn anode enables the full cell to deliver satisfactory rate performance and a 97% capacity retention over 1600 cycles. This work provides a simple strategy for the effective preparation of highly reversible zinc anodes for high‐performance aqueous zinc‐ion batteries.

Unveiling the Failure Mechanism of Zn Anodes in Zinc Trifluorosulfonate Electrolyte: The Role of Micelle-like Structures.

Zinc trifluorosulfonate [Zn(OTf)2] is considered as the most suitable zinc salt for aqueous Zn-ion batteries (AZIBs) but cannot support the long-term cycling of the Zn anode. Here, we reveal the micelle-like structure of the Zn(OTf)2 electrolyte and reunderstand the failing mechanism of the Zn anode. Since the solvated Zn2+ possesses a positive charge, it can spontaneously attract OTf- with the hydrophilic group of -SO3 and the hydrophobic group of -CF3 via electrostatic interaction and form a "micelle-like" structure, which is responsible for the poor desolvation kinetics and dendrite growth. To address these issues, an antimicelle-like structure is designed by using ethylene glycol monomethyl ether (EGME) as a cosolvent for highly reversible AZIBs. The modified electrolyte shows lower dissociation ability to Zn(OTf)2 and higher coordination tendency with Zn2+ compared to the Zn(OTf)2 electrolyte, resulting in the unique solvation structure of Zn2+(H2O)1.2(OTf-)2(EGME)2.8, which significantly reduces the charge of micelle, damages the micelle-like structure, and boosts the desolvation kinetics. Moreover, the reduction of EGME and OTf- can form a robust dual-layered SEI with high Zn2+ ion conductivity. Consequently, the Zn/Cu asymmetric coin cell using ZT-EGME can work at a high rate and a capacity of 50 mA cm-2 and 5 mA h cm-2 for more than 120 cycles, while its counterparts using ZT can barely work. Moreover, a 505.1 mA h pouch cell with practical parameters including a lean electrolyte supply of 15 mL A h-1 and an N/P ratio of ∼3.5 can work for 50 cycles.

Pre-Intercalation of TMA Cations in MoS2 Interlayers for Fast and Stable Zinc Ion Storage.

Applications of aqueous zinc ion batteries (ZIBs) for grid-scale energy storage are hindered by the lacking of stable cathodes with large capacity and fast redox kinetics. Herein, the intercalation of tetramethylammonium (TMA+) cations is reported into MoS2 interlayers to expand its spacing from 0.63 to 1.06nm. The pre-intercalation of TMA+ induces phase transition of MoS2 from 2H to 1T phase, contributing to an enhanced conductivity and better wettability. Besides, The calculation from density functional theory indicates that those TMA+ can effectively shield the interactions between Zn2+ and MoS2 layers. Consequently, two orders magnitude high Zn2+ ions diffusion coefficient and 11 times enhancement in specific capacity (212.4vs 18.9 mAh g‒1 at 0.1 A g‒1) are achieved. The electrochemical investigations reveal both Zn2+ and H+ can be reversibly co-inserted into the MoS2-TMA electrode. Moreover, the steady habitat of TMA+ between MoS2 interlayers affords the MoS2-TMA with remarkable cycling stability (90.1% capacity retention after 2000 cycles at 5.0 A g‒1). These performances are superior to most of the recent zinc ion batteries assembled with MoS2 or VS2-based cathodes. This work offers a new avenue to tuning the structure of MoS2 for aqueous ZIBs.

Enhancement of CO2 separation efficiency in mixed matrix membranes through zinc ion modified g‐C3N4 nanosheets

AbstractThis study employed modified graphitic carbon nitride (g‐C3N4) nanosheets and polyether block amide (Pebax) to prepare mixed matrix membranes (MMMs) aiming to enhance CO2 separation efficiency. Through sulfonation and zinc ion (Zn2+) modification of g‐C3N4 nanosheets, high Zn2+ loaded nanofillers (SCN‐Zn2+) were synthesized. Compared to g‐C3N4, MMMs with SCN‐Zn2+ as nanofiller showed a CO2 permeance of 462 Barrer as well as the CO2/N2 selectivity of 47.5 at the feed gas pressure of 2 bar, which surpassed the 2008 Robeson upper bound. Additionally, the Pebax/SCN‐Zn2+(30) membrane was subjected to continuous gas permeability experiments for 70 h and showed good stability. The results showed that SCN‐Zn2+ nanosheets played an important role in enhancing the gas selectivity of the membranes. SEM confirmed that the SCN‐Zn2+ nanosheets had good compatibility with the Pebax substrate and the presence of hydrophilic sulfonic acid groups effectively suppressed the interfacial defects. The increase in the free volume fraction of the membranes as well as the solubility and diffusion coefficient suggested that the introduction of g‐C3N4 nanosheets led to more tortuous gas transport paths, which enhanced the permeability and selectivity of CO2.