Cathodic Dissolution Research Articles

Zn metal anodes stabilized by an intrinsically safe, dilute, and hydrous organic electrolyte

Rechargeable Zn batteries hold great promise for large-scale energy storage applications but their reversibility is limited by non-compact and dendritic Zn deposition along with interfacial parasitic reactions in conventional electrolytes. Herein, we report an intrinsically safe, dilute, and hydrous organic electrolyte by coupling hydrated Zn(BF4)2 salt with trimethyl phosphate (TMP) solvent for highly reversible Zn batteries, without the need of concentrated electrolyte strategies. The formulated 1 m Zn(BF4)2/TMP enables spatially compact, dendrite-free, and corrosion-free Zn electrodeposition even at high areal capacity (5 and 10 mAh cm−2) using a pressure-free electrolytic cell. Moreover, the hydrous organic electrolyte with low water activity expands the electrochemical window to 3 V (versus Zn2+/Zn) and in-situ forms a protective ZnF2-Zn3(PO4)2-rich interphase on Zn. The resultant Zn electrode achieves long-term cycling over 4200 h with a superhigh cumulative plating capacity of 10500 mAh cm−2 under 5 mA cm−2 in Zn//Zn cell and exhibits high efficiency of 99.5% over 600 cycles in Zn//Cu cell (1 mA cm−2; 1 mAh cm−2). Moreover, this electrolyte supports the stable operation of a full Zn//V2O5·nH2O battery by significantly suppressing cathode dissolution. This work would enlighten the design of hydrous organic electrolytes for practical Zn batteries.

In Situ Multi-Modal Approach for Electrode-Electrolyte Interfacial Chemistryand Electrode and Electrolyte Aging Behavior Studies

Increasing demands for cost-effective electric vehicles and electrochemical energy storage systems require advanced secondary batteries with higher energy density, longer lifetime, and enhanced safety. Increase of the battery operating voltage is one realistic strategy to extend the energy density, but it is accompanied by irreversible structural changes to the electrodes and parasitic reactions within an electrode-electrolyte interphase resulting in capacity fading and subsequent battery failure. Therefore, a fundamental understanding of underlying electrochemical mechanisms in the electrodes during battery cycling is critical for the development of next-generation secondary batteries.Based on our previous studies utilizing in situ surface-enhanced Raman spectroscopy to monitor the evolution of the Si-electrolyte interphase1 and in situ ATR-FTIR to investigate the voltage dependent electrolyte solution structure changes at the interface, transition metal redox chemistry, and cathode/electrolyte interfacial layer evolution,2 recently we updated the in situATR-FTIR with a newly designed ‘full-cell’ that enables us to analyze the interfacial reactions and interactions on the surfaces of both electrodes that directly influence battery performance, lifetime, and safety. Specifically, we focus on transition metal complex formation and its effect on solid-electrolyte interphase (SEI) formation and evolution on the anode due to transition metal dissolution and crosstalk of Mn-rich cathodes at high voltages (≥4.4 V).In addition, using our multi-modal characterization—a combination of in situ gas chromatography with flame ionization detection (GC-FID) and in situ ATR-FTIR—(electro)chemical degradation of the electrolyte is correlated with gas evolution in the battery. For example, GC-FID measures increasing amounts of ethylene gas until the end the first charging cycle of a LiNiO2//Graphite cell with Gen2 electrolyte (LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC), 3:7 wt.%). Concurrently, in situ ATR-FTIR shows decreasing concentration of EC solvent, as calculated from the FTIR intensity of EC vibrational absorption. Ethylene is a known by-product of ethylene carbonate electrochemical reduction and is produced during SEI formation.3 Quantifying multiphase reactions occurring during battery operation is critical to understanding and mitigating battery degradation pathways, and developing next-generation battery materials systems.

Optimisation of nickel extraction from spent cathodes of NiMH batteries by hydrometallurgical process through experimental design

ABSTRACT This paper presents the development of a novel process for the extraction of Ni contained in spent cathodes of NiMH batteries, by using an organic leaching agent, acetic acid (CH3COOH), in the presence of hydrogen peroxide (H2O2) as a facilitator of cathodic dissolution. The operating parameters studied were temperature, time, and concentration of CH3COOH and H2O2, applying experimental design with subsequent optimisation using the response surface methodology (RSM). The maximum empirical extraction of Ni, of 99.9%, was achieved under the following conditions: temperature, 75°C; CH3COOH and H2O2 concentrations, 6% (v/v) and 1.5% (v/v), respectively; reaction time, 30 min; stirring speed, 330 rpm and solid–liquid ratio, 25 g/L. To minimise the values of parameters such as the temperature and concentration of leaching agent and H2O2, a numerical optimisation was carried out, leading to an optimal extraction value of 95.6%.

Suppressing vanadium dissolution in 2D V2O5/MXene heterostructures via organic/aqueous hybrid electrolyte for stable zinc ion batteries

Zinc ion batteries (ZIBs) have become a promising candidate for next-generation large-scale energy storage devices due to the intrinsic safety and low cost. However, their practical applications are seriously impeded by unsatisfying cycling life mainly due to the cathode dissolution in traditional aqueous electrolytes. Herein, we propose an organic/aqueous hybrid electrolyte (Zn(OTf)2-TEP/H2O) made of zinc triflate (Zn(OTf)2) salt in triethyl phosphate (TEP) and H2O solvents to pair with two-dimensional (2D) vanadium hydrate oxide/Ti3C2 MXene heterostructure cathodes (V2O5·1.6H2O/MXene), which functions to greatly enhance the stability of the ZIBs. Benefiting from the suitable ionic conductivity of 5.81 mS cm−1, moderate de-solvation barrier of 0.26 eV, wide voltage window of 0.1–1.9 V and superior ability of inhibiting vanadium dissolution, the optimized organic/aqueous hybrid electrolyte with 80 % TEP in volume (Zn(OTf)2-TEP/H2O-80%) endowed V2O5·1.6H2O/MXene cathodes with superior zinc storage performance, evidenced by a high capacity of 117.8 mAh g−1 after 4000 cycles and a capacity retention of 78.6 % at 0.5 A g−1. We have shown that the reversible Zn2+ intercalation/deintercalation mechanisms are responsible for the excellent zinc storage performance. It is believed that the novel organic/aqueous hybrid electrolyte reported here may pave a new way to construct durable ZIBs.

Electrolyte additive engineering for aqueous Zn ion batteries

Aqueous Zn ion batteries (AZIBs) are one of the most promising new-generation electrochemical energy storage devices with high specific capacity, good security, and economic benefits. The electrolyte acts as a bridge connecting cathode and anode, providing a realistic working environment. However, using aqueous electrolytes presents many challenges for cathode (dissolution, electrostatic interaction, by-products) and anode (Zn dendrite, side reactions). As an innovative and maneuverable technology, additive engineering has effectively solved electrodes' critical problems. Therefore, it is essential to systematically summarize additive engineering and explore new perspectives in response to the existing issues. Based on the challenges of electrolytes for electrodes, the review focuses on an overview of the effects of additive engineering on cathode and anode, respectively. Additive engineering can improve the problems existing in the cathode, such as relieving dissolution, adjusting electrostatic interaction, and reducing by-products. The effects on anode are summarized in aspects of inhibiting Zn dendrites and reducing side reactions. In addition, the effects of different additives on the charge storage mechanism as well as the kinetic characteristics of AZIBs are described separately. Finally, the potential directions and development prospects for further improvement of additive engineering in AZIBs are proposed. In this review, we retrospect the challenges faced by the cathode and anode of AZIBs during the use of aqueous electrolytes. As an innovative and maneuverable technology, additive engineering can be used to effectively solve most of the critical problems of cathode and anode. Thus, a comprehensive overview of additive engineering strategies is presented from a new perspective of function and mechanism. Finally, potential directions and development prospects for further improvement of additive engineering in AZIBs are presented based on the authors’ best knowledge.

Triple‐Functional Polyoxovanadate Cluster in Regulating Cathode, Anode, and Electrolyte for Tough Aqueous Zinc‐Ion Battery

AbstractDespite a promising outlook due to the intrinsic low cost and high safety, the practical application of aqueous Zn‐ion battery is impeded by the severe mutual problems of cathode dissolution, electrolyte parasitic reactions, and metallic anode dendrite growth. Herein, a triple‐functional strategy is proposed that a polyoxovanadate (POV) cluster of K10[VIV16VV18O82] as a promising Zn2+ host can concomitantly stabilize the cluster cathode, aqueous electrolyte, and metallic Zn anode. An in situ generated cathode electrolyte interface via anodic oxidation is identified as effective in preventing the dissolution of POV cathode. Molecular dynamics simulation and density functional theory calculation confirm that the [VIV16VV18O82]10− polyoxoanions can synergistically suppress electrolyte side reactions by modulating the primary solvation shell of Zn2+‐6H2O, and random anode dendrite growth by in situ constructing a stable solid electrolyte interface of Zn‐POV. As a result, the Zn//POV battery exhibits unprecedented cycling durability over 10 000 cycles at high rates of 5 and 12 A g−1. In a systematic consideration, the findings enlighten the origin of triple‐functional polyoxometalates and will significantly propel the practical development of aqueous batteries.

Synergetic Modulation of Ion Flux and Water Activity in a Single Zn2+ Conductor Hydrogel Electrolyte for Ultrastable Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (ZIBs) suffer from dendrite growth, hydrogen evolution reaction (HER), and cathode dissolution. To overcome the above issues, we designed a single Zn2+ conductor hydrogel electrolyte (poly 3-sulfopropyl acrylate zinc, PSPAZn) through UV photopolymerization of the designed monomer zinc salt of SPAZn. The polymerized and fixed anion chains with single Zn2+-conducting characteristics not only promote the uniform distribution of Zn2+ ion flux by charge interaction but also decrease the concentration polarization, leading to nondendrite Zn deposition behavior. Meanwhile, the water activity is significantly reduced due to abundant hydrophilic groups in polymer side chains, effectively inhibiting HER and the dissolution of cathode materials. Consequently, the lifespan of a zinc anode with PSPAZn electrolyte is extended to more than 3000 h, and the Zn/MnO2 full ZIBs also exhibit a high capacity retention of 77.1% after 220 cycles without MnSO4 additive. Such a simple kilogram-scale preparation strategy should offer opportunities for developing practical ZIBs.

In-situ induced self-solidification and activation of ultra-high energy density organic cathode

• We have developed a method of in situ electrochemical polymerization that the terminal-acetylene coupling occurs at high operating voltage (4.5 V vs. Li/Li + ) without Cu elements. This is a very effective method to show that the kinetic performance and the long-term stability of the molecular cathode are greatly improved. • Utilization of the general approach, the assembly engineering of organic battery is unprecedentedly simplified, and the cathode based on 2,7-diethylnylpyrene-4,5,9,10-tetraone delivers an ultrahigh capacity of 411 mAh/g with a robust retention in 1000 cycles. The energy density is raised up to 955 Wh/kg. Our results demonstrate that such a method has broad application prospects in organic batteries with high energy density. • Significantly, this approach activates the new positions of the diyne linkage for storing anions, efficiently compensating the capacity decline caused by the introduction of nonactive unit in the polymerization approach. • PTO-diyne providing a high reversible capacity of 411 mAh/g over 1000 cycles. The strong dissolution and short conductivity of organic molecular cathodes restrict their rapid development. To overcome these bottlenecks, it is imperative to develop an effective polymerization method while maintaining their high capacities. To overcome these issues, the method of in situ electrochemical polymerization has been developed that the terminal-acetylene coupling occurs at high operating voltage without Cu elements. Such electrochemical coupling leads to the polymerization of organic molecular cathodes and thus in situ self-solidified at the current collector. This is a very effective method to show that the kinetic performance and the long-term stability of the molecular cathode are greatly improved. What is significant is that this process successfully activates the diyne bonds, leading to the capacity to store anions at high operating platform for the first time was observed, which more than compensates for the reduction in specific capacity. Utilization of the general approach, the assembly engineering of organic battery is unprecedentedly simplified, and the cathode based on 2,7-diethylnylpyrene-4,5,9,10-tetraone delivers an ultrahigh capacity of 411 mAh/g with a robust retention in 1000 cycles. The energy density is raised up to 955 Wh/kg. Our results demonstrate that such a method has broad application prospects in organic batteries with high energy density.

Regulating Water Activity for Rechargeable Zinc-Ion Batteries: Progress and Perspective

Recent emerging rechargeable zinc-ion batteries have inherent benefits of intrinsic battery safety and high elemental abundance and reduce pollution toward an environmentally compatible energy storage system. However, the effort of promoting rechargeable aqueous Zn-ion batteries for large-scale energy storage applications is greatly plagued by the high activity of water molecules. The high activity of water molecules remains a threat to Zn-ion batteries, leading to premature failure of the Zn anode, cathode dissolution, and inferior low-temperature performance. Recently, a wide spectrum of effective strategies has been reported for reducing water’s activity to tackle the above challenges. In view of the shallow understanding of water molecule states and their interwoven associations with Zn-ion battery performance, it becomes urgent to highlight the significance of regulating water activity and summarize recent progress in aqueous Zn-ion batteries. This Perspective aims to provide a fundamental understanding for designing better Zn-ion batteries using aqueous solution chemistry.

New Insights into Pt Dissolution Mechanisms from SFC-ICP-MS Measurements for Well-Defined Surfaces

In the last years, polymer electrolyte membrane fuel cell (PEMFC) technology has progressed notably, allowing its extended implementation in the transport sector. For example, the fuel cell cars currently being commercialized use PEMFCs with Pt nanoparticles for the oxygen reduction reaction (ORR) at the cathode, primarily because of their better long-term stability in comparison to other electrocatalysts. However, even pure Pt catalysts degrade under real-life conditions, since a PEMFC is expected to resist hundreds of thousands of load cycles and tens of thousands of start-up/shut-down cycles during its lifetime, leading to a high number of platinum oxidation/reduction cycles and resulting in its extensive degradation.1 This degradation of Pt catalysts is mainly linked to electro-oxidation and dissolution processes, which have been investigated for a long time in polycrystalline and supported nanoparticle catalysts. More recently, investigations with Pt single crystal electrodes have been carried out, which offer the possibility of a more detailed understanding of these processes at the atomic level. These works include studies using in-situ surface X-ray diffraction (SXRD) and on-line inductively coupled mass spectrometry (ICP-MS), which have for example shown differences in the onset potential for anodic dissolution on Pt(100) and Pt(111) that have their origin in the different atomic structures of the initial oxide.2 The present work focuses on the dissolution behaviour of the well-defined surfaces of the three Pt basal planes investigated by scanning flow cell inductively coupled mass spectrometry (SFC-ICP-MS). Further investigations providing new information about the dissolution mechanisms are carried out by varying a wide variety of parameters: upper potential limit, scan rate, potential holding times, electrolyte composition, pH, purging gas and cooling atmosphere. Some of the results will be presented in combination with SXRD measurements in order to explain different aspects of the restructuring and dissolution mechanisms for these surfaces. For example, the dissolved amounts for Pt(111), Pt(100) and Pt(110) in 0.1 M HClO4 and 0.1 M H2SO4 after cyclic voltammetry at a scan rate of 0.05 V s-1 for three different upper potential limits, 1.20 V, 1.40 V and 1.60 V vs. RHE, were obtained. In all cases dissolution follows the order Pt(110) > Pt(100) > Pt(111), which is in agreement with the previous works performed in 0.1 M HClO4.3 Higher dissolution is always observed in the case of H2SO4 electrolyte. Potentiostatic hold experiments for Pt(100) have been carried out, allowing the separation of the anodic and cathodic dissolution peaks. It can be observed that the cathodic dissolution increases proportionally with the increase in the oxidation potential. The combination of this data with SXRD measurements suggests that there are specific species in the oxide structure at high potentials that are the responsible for the majority of the cathodic dissolution in the Pt(100) surface.References M. K. Debe, Nature, 486 (2012) 43-51.Fuchs, T.; Drnec, J.; Calle-Vallejo, F.; Stubb, N.; Sandbeck, D.; Ruge, M.; Cherevko. S.; Harrington, D. A.; Magnussen, O. M. Nature Catalysis 3 (2020) 754-761.Sandbeck, D. J. S.; Brummel, O.; Mayrhofer, K. J. J.; Stubb, N.; Libuda, J.; Katsounaros, I.; Cherevko. S. ChemPhysChem 20 (2019) 2997-3003

Fered-Fenton treatment of car wash wastewater using carbon felt cathode: Carbon dissolution and cathodic corrosion

The Fered-Fenton (FF) process has the potential to oxidize organic pollutants in car wash wastewater (CWW) nonselectively. As a high-quality gas diffusion cathode, carbon felt (CF) is perhaps one of the most widely used carbon cathodes in FF process. Although thermodynamic instability has been found, there are no clear reports on the negative effects on organics evolution and possible ways of cathodic corrosion of CF. This study first report the carbon dissolution and cathodic corrosion of CF cathode and revealed a possible corrosion pathway. An FF system using carbon felt cathode was constructed that can effectively remove chemical oxygen demand (COD), total organic carbon (TOC) and linear alkylbenzene sulfonate (LAS) of CWW in 120 min. During electrolysis, carbon dissolution of the CF cathode leads to the accumulation of organic carbon. Toxic organic intermediates were detected and negatively affected biodegradability and acute cytotoxicity. The main cause of cathodic corrosion was the electroreduction of carbon species on CF. Hydrogen peroxide indirectly promoted the corrosion process by consuming reducing carbon species. Optimizing the appropriate electrolysis time (such as 60 min) or using a more stable graphite felt (GF) cathode as an alternative is the recommended strategy. This work provides new insight and technical support for the FF process with CF cathode.

Synthesis of Amine Grafted Poly (Acrylic-Maleic) as an efficient inhibitor against stainless steel corrosion in a highly saline medium

In this study, a novel amine grafted poly-(acrylic maleic) (APAM) was synthesized and its efficiency was investigated against the corrosion of stainless steel 316 L in simulated saline (3.5 % NaCl) environment using electrochemical and weight loss experiments at various temperatures i.e. 25, 40 and 60 °C. The synthesized compound was characterized by FTIR, proton, and carbon-13 NMR techniques. The compound performed excellently and was observed to function as a mixed-type inhibitor, inhibiting both the cathodic hydrogen evolution and anodic iron dissolution reactions. The adsorption of APAM molecules obeyed the Langmuir adsorption theory and the estimated values of ∆Gado obtained using weight and PDP data suggest that APAM adsorbed on the steel surface by both the chemisorption and physiosorption mechanisms. APAM molecules adsorbed to the steel surface to create an APAM layer that inhibits the corrosive medium from reaching the surface, according to surface morphological observations and examination of the protected steel surface using SEM, EDS, AFM, and FTIR spectra.

A piece of common cellulose paper but with outstanding functions for advanced aqueous zinc-ion batteries

Aqueous zinc-ion batteries are considered to be one of the most promising next-generation large-scale energy storage devices owing to their abundant raw material resources, high safety, and cost-effectiveness. However, the uncontrollable zinc dendrite growth and cathode dissolution severely deteriorate the cycling performance of the batteries, thus hindering their practical application. Herein, we directly implant a commercially available cellulose paper at the glass fiber-zinc anode interface to improve the overall battery performance. The highly zincophobic cellulose paper can induce lateral zinc growth on the surface and alleviate by-product accumulation at the interface by its poor electrolyte affinity and retention. Besides, the nanoporous cellulose paper with abundant hydroxyl groups strongly adsorbs vanadium ions dissolved from the cathode and prevents the shuttle of vanadium ions to the anode interface. As a result, the assembled NH4V4O10//Zn full cell with cellulose paper exhibits an outstanding long cycle life of 850 cycles with the capacity retention of 89% at a current density of 4 A g−1. This strategy offers an emerging avenue to design sustainable and low-cost separators for high-performance aqueous zinc-ion batteries.

Corrosion protection enhancement of Mg alloy WE43 by in-situ synthesis of MgFe LDH/citric acid composite coating intercalated with 8HQ

A composite coating consisting of Mg-Fe LDH intercalated with 8-hydroxyquinoline (8HQ) and modified with citric acid (CA) layer is constructed on Mg alloy WE43 via combination of electrodeposition, hydrothermal and anion-exchange. In view of CA and their small "island-shaped" surface morphology, the CA coating could provide MgFe LDH film with physical and chemical shielding. The intercalation of 8HQ into the MgFe LDH/0.05CA saw further enhancement in corrosion resistance as 8HQ hinders anodic and cathodic dissolution reaction. Furthermore, the MgFe-8HQ LDH/0.05CA coating presented a possible self-healing based on the 7-day EIS study, establishing as a potential coating for biomedical implant applications.

Facile large-scale preparation of vanadium pentoxide -polypyrrole composite for aqueous zinc-ion batteries

Aqueous zinc-ion batteries (ZIBs) have been noted as promising large-scale energy storage systems owing to their cost-effective and environmentally friendly merits. However, the further development of ZIBs is limited by suitable cathodes, which normally suffer from the challengers of cathode dissolution, poor electronic conductivity, and low ion diffusion coefficient. Herein, we adopted a simpler, prone largescale preparation strategy of in situ polymerization at room temperature to prepare V2O5-polypyrrole (V2O5-PPy) nanobelt composite that the V2O5 act as an oxidant for pyrrole (Py) polymerization, and Py in situ polymerized on the V2O5. The V2O5-PPy nanobelt composite contributes to preventing the dissolution of vanadium elements, improving electronic conductivity, and forming oxygen vacancies (Vö). As a result, an excellent initial discharge capacity of 441 mAh g−1 at 0.1 A g−1 and 291 mAh g−1 at a high current density of 5 A g−1 was realized. More importantly, a capacity retention rate of 95.92% after the long-term 2000 cycles at a high current density of 5 A g−1 was achieved. The capacitance control is dominant and accounts for 80.76% at 0.5 mV s−1, and the zinc ion diffusion coefficient during the cycle is 4.4 × 10−8-1.62 × 10−9 cm2 S−1, indicating good kinetics. Our work provides a feasible strategy for the large-scale fabrication of V2O5-PPy for ZIBs.

Unraveling the role of introduced W in oxidation tolerance for Pt-based catalysts via on-line inductive coupled plasma-mass spectrometry

Water electrolysis cells and fuel cells have attracted considerable attention because they provide renewable and sustainable energy conversion and storage systems. Pt is the best catalyst for these two devices. However, cathodic Pt dissolution can occur after the oxidation of Pt, degrading the Pt catalyst. We report a PtW/C catalyst with high oxidation tolerance under repeated reverse-potential tests. The prepared PtW/C catalyst possesses higher oxidation tolerance than does the commercial Pt/C catalyst under repeated reverse-potential tests while showing comparable catalytic activity. From a combination of on-line inductively coupled plasma-mass spectrometry (ICP-MS) and ex-situ spectroscopy, we suggest that cathodic Pt dissolution is significantly inhibited because the introduced W suppresses the oxidation of Pt in PtW/C. However, W is dissolved in PtW/C rather than in Pt, indicating the need for further research. Our study demonstrates a new perspective for developing Pt-based catalysts with high oxidation tolerance by reducing cathodic Pt dissolution.

Construction of Bio-inspired Film with Engineered Hydrophobicity to Boost Interfacial Reaction Kinetics of Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries typically suffer from sluggish interfacial reaction kinetics and drastic cathode dissolution owing to the desolvation process of hydrated Zn2+ and continual adsorption/desorption behavior of water molecules, respectively. To address these obstacles, a bio-inspired approach, which exploits the moderate metabolic energy of cell systems and the amphiphilic nature of plasma membranes, is employed to construct a bio-inspired hydrophobic conductive poly(3,4-ethylenedioxythiophene) film decorating α-MnO2 cathode. Like plasma membranes, the bio-inspired film can "selectively" boost Zn2+ migration with a lower energy barrier and maintain the integrity of the entire cathode. Electrochemical reaction kinetics analysis and theoretical calculations reveal that the bio-inspired film can significantly improve the electrical conductivity of the electrode, endow the cathode-electrolyte interface with engineered hydrophobicity, and enhance the desolvation behavior of hydrated Zn2+ . This results in an enhanced ion diffusion rate and minimized cathode dissolution, thereby boosting the overall interfacial reaction kinetics and cathode stability. Owing to these intriguing merits, the composite cathode can demonstrate remarkable cycling stability and rate performance in comparison with the pristine MnO2 cathode. Based on the bio-inspired design philosophy, this work can provide a novel insight for future research on promoting the interfacial reaction kinetics and electrode stability for various battery systems.

Deciphering and suppressing the cathode dissolution catastrophe in aqueous rechargeable dual-ion battery

The development of aqueous dual-ion batteries (DIBs) has been hampered by two omnipresent issues, i.e. limited ESW of electrolyte and unsatisfactory electrode dissolution. In this study, a new DIB concept based on Cl[Formula: see text] and Na[Formula: see text] dual ion shutting with a sodium chloride (NaCl) aqueous electrolyte was reported. The electrochemical stable window (ESW) of the aqueous electrolyte was improved by inducing the urea to stabilize the shared water (H2O) molecule in the solvation sheath around Na[Formula: see text] and Cl[Formula: see text] based on the “water-in-salt” mechanism. Furthermore, an artificial SEI layer was introduced to inhibit the dissolution of Na3V[Formula: see text]Fe[Formula: see text](PO[Formula: see text] (Fe-NVP) cathode, thus ensuring a good cycling stability over 300 cycles of the aqueous DIB with an average discharging voltage of [Formula: see text]0.67 V. These exciting results advance the fundamental understanding of the artificial protective SEI and high-performance “water-in-salt” electrolyte design in developing cheap, stable aqueous DIB systems.

Zinc-Ion Storage Mechanism of Polyaniline for Rechargeable Aqueous Zinc-Ion Batteries.

Aqueous multivalent ion batteries, especially aqueous zinc-ion batteries (ZIBs), have promising energy storage application due to their unique merits of safety, high ionic conductivity, and high gravimetric energy density. To improve their electrochemical performance, polyaniline (PANI) is often chosen to suppress cathode dissolution. Herein, this work focuses on the zinc ion storage behavior of a PANI cathode. The energy storage mechanism of PANI is associated with four types of protonated/non-protonated amine or imine. The PANI cathode achieves a high capacity of 74 mAh g−1 at 0.3 A g−1 and maintains 48.4% of its initial discharge capacity after 1000 cycles. It also demonstrates an ultrahigh diffusion coefficient of 6.25 × 10−9~7.82 × 10−8 cm−2 s−1 during discharging and 7.69 × 10−10~1.81 × 10−7 cm−2 s−1 during charging processes, which is one or two orders of magnitude higher than other reported studies. This work sheds a light on developing PANI-composited cathodes in rechargeable aqueous ZIBs energy storage devices.

Low-cost and long-life Zn/Prussian blue battery using a water-in-ethanol electrolyte with a normal salt concentration

Although rechargeable aqueous Zn-ion batteries (ZIBs) are very attractive as one of the most promising energy storage systems with merits of low cost, environmental friendliness, high power density and high safety, practical applications of ZIBs are largely limited by Zn corrosion, Zn dendrite growth and cathode dissolution. In this work, a cost-effective water/ethanol hybrid (WEH) electrolyte with a normal salt concentration was proposed to solve the above issues in Daniell-type zinc/manganese Prussian blue (MnPB) battery with MnPB cathode and Zn anode. The unique WEH electrolyte endows the batteries with a high specific capacity of ∼80 mAh g–1, superior rate capability with 90.4% capacity yielded at 50 C relative to 0.5 C, and an extremely stable cycling with 91.6% capacity retained after 20000 cycles at 5 C (the cycling time lasts as long as ∼ 1 year). Dendrite-free Zn stripping/deposition is confirmed by in situ optical microscopy and first-principles calculation. Pouch-type batteries were assembled which exhibit stable cycling and easy scale up in capacity and voltage by connecting cells in series and parallel. A low-cost strategy was further demonstrated by using low-concentration salt, cheap salt (Na2SO4) and waste liquor. This work provides a practical strategy to design low-cost, environmentally friendly and high-performance Zn-based batteries.