Application In Rechargeable Batteries Research Articles

Challenges and Prospects of Low-Temperature Rechargeable Batteries: Electrolytes, Interfaces, and Electrodes.

Rechargeable batteries have been indispensable for various portable devices, electric vehicles, and energy storage stations. The operation of rechargeable batteries at low temperatures has been challenging due to increasing electrolyte viscosity and rising electrode resistance, which lead to sluggish ion transfer and large voltage hysteresis. Advanced electrolyte design and feasible electrode engineering to achieve desirable performance at low temperatures are crucial for the practical application of rechargeable batteries. Herein, the failure mechanism of the batteries at low temperature is discussed in detail from atomic perspectives, and deep insights on the solvent-solvent, solvent-ion, and ion-ion interactions in the electrolytes at low temperatures are provided. The evolution of electrode interfaces is discussed in detail. The electrochemical reactions of the electrodes at low temperatures are elucidated, and the approaches to accelerate the internal ion diffusion kinetics of the electrodes are highlighted. This review aims to deepen the understanding of the working mechanism of low-temperature batteries at the atomic scale to shed light on the future development of low-temperature rechargeable batteries.

Innovative Air Cathode with Ni-Doped Cobalt Sulfide in Highly Ordered Macroporous Carbon Matrix for Rechargeable Zn-Air Battery.

To realize the practical application of rechargeable Zn-Air batteries (ZABs), it is imperative to develop a non-noble metal-based electrocatalyst with high electrochemical performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Herein, Ni-doped Co9S8 nanoparticles dispersed on an inverse opal-structured N, S co-doped carbon matrix (IO─NixCo9-xS8@NSC) as a bifunctional electrocatalyst is presented. The unique 3D porous structure, arranged in an inverse opal pattern, provides a large active surface area. Also, the conductive carbon substrate ensures the homogeneous dispersion of NixCo9-xS8 nanocrystals, preventing aggregation and increasing the exposure of active sites. The introduction of heteroatom dopants into the Co9S8 structure generates defect sites and enhances surface polarity, thereby improving electrocatalytic performance in alkaline solutions. Consequently, the IO─NixCo9-xS8@NSC shows excellent bifunctional activity with a high half-wave potential of 0.926V for ORR and a low overpotential of 289mV at 10mA cm-2 for OER. Moreover, the rechargeable ZAB assembled with prepared electrocatalyst exhibits a higher specific capacity (768 mAh gZn -1), peak power density (180.2mW cm-2), and outstanding stability (over 160h) compared to precious metal-based electrocatalyst.

An Organic Acid-Alkali Coregulated Ionic Liquid Electrolyte Enabling Wide-Temperature-Range Proton Battery.

The broad applications of rechargeable batteries urge people to develop alternative energy storage devices with sustainable resources, high capacity, long cycling life, and wide-temperature operability. Aqueous proton batteries are considered as a state-of-the-art energy storage system due to their intrinsic safety and low cost. However, aqueous electrolytes have a low boiling point and narrow electrochemical stability window, limiting their applications in wide-temperature and high-energy batteries. Herein, a hybrid organic ionic liquid electrolyte with organic alkali 1-methyl-1,2,4-triazole (MTA) protonated by organic acid bis(trifluoromethysulfonyl)imide (HTFSI) as proton carriers and tetramethylene sulfone (TMS) as the solvent, noted as HTFSI-MTA-TMS, exhibited the stable electrochemical windows exceeding 5V at -20°C and 3.5V at 80°C. Benefiting from this electrolyte, the assembled MnO2-S//MoO3 button proton full battery can display an operation voltage up to 1.8V, energy density of 44.8Wh kg-1, and good cycling stability at room temperature when bis(trifluoromethanesulfonyl)imide manganese (II) salt (Mn(TFSI)2) is introduced into the electrolyte, and run well in a wide-temperature range (-20°C-60°C). The work reveals the potential of organic acid-alkali coregulated electrolytes to meet the need of energy storage in a wide-temperature range and will advance the development of high-energy proton batteries.

Boosting OER activity of Fe-N Moieties via Ni induced d-Orbital Tailoring for durable rechargeable Zn-Air batteries

Fe-N-C-based catalysts are considered the most promising Pt candidates due to their high oxygen reduction reaction (ORR) activity and low cost, whereas their oxygen evolution reaction (OER) performance is extremely poor due to the sluggish O-O coupling process, which hampers the practical application of rechargeable zinc-air batteries. Here, we in situ infiltrate Ni and Fe ions into metal triazolidine (MET)-derived N-doped porous carbon via a microporous confinement-pyrolysis strategy to enhance the OER activity of the Fe-N sites. The introduction of Ni induced the electronic delocalization of Fe atoms at the Fe-N center, which lowered the adsorption energy barriers for the decisive velocity step (O*→OOH*), thus accelerating the O-O bond coupling and OER kinetics. In addition, the preferential formation of NiOOH at high OER potentials ensures the catalytic stability of zinc-air batteries by trapping Fe ions escaping from carbon corrosion to form FeOOH. The optimized catalyst (FeNi-NC) has an overpotential of only 351 mV at a current density of 50 mA cm−2 under alkaline conditions. More importantly, the assembled ZABs can be stably charged and discharged for more than 500 h at 10 mA cm−2, demonstrating excellent battery charging and discharging stability. This work shows the great potential of strong electronic interactions between polymetals to improve Fe-N-C catalysts.

Highly asymmetrically configured single atoms anchored on flame-roasting deposited carbon black as cathode catalysts for ultrahigh power density Zn-air batteries

Iron group element-based single atom (SA) catalysts are highly regarded as promising alternatives to commercial Pt/C for catalysis of oxygen reduction reaction (ORR). For applications in rechargeable zinc-air batteries (ZABs), achieving the necessary high catalytic efficiency of the SAs toward oxygen evolution reaction (OER) however remains a significant challenge. Here, highly asymmetrically configured Fe SAs created with N,S co-coordination and anchored on flame-roasting deposited carbon black (CB), Fe-N3S1/CB, are developed, achieving outstanding bifunctional oxygen catalytic efficiency, with an ultra-small potential gap of 0.661 V at 10 mA cm-2 (ΔE10), outperforming the (Pt/C+RuO2) composite catalyst (0.697 V). With a newly proposed binder-free composite air cathode design, the Fe-N3S1/CB based ZAB achieves an ultrahigh power density of 365.7 mW cm-2 at a current density of 511.3 mA cm-2, largely outperforming the (Pt/C+RuO2) based ZAB (225.9 mW cm-2 at 344.7 mA cm-2). Furthermore, the Fe-N3S1/CB based ZAB demonstrates excellent long-term stability, with only 8.2% decay in round-trip efficiency over 1000 (333.3 h) charge-discharge cycles at 10 mA cm-2. Density functional theory calculations elucidate that incorporation of sulfur into the coordination sphere of Fe facilitates the electrochemical dehydroxylation step for ORR and accelerates the electrochemical O2 desorption step for OER, thereby reducing the corresponding free energy differences on Fe SAs for largely enhanced catalytic efficiency.1. A large size hetero-atom element, sulfur, is introduced to create highly asymmetrically configured Fe single atoms for enhancements in catalytic efficiency toward both oxygen reduction reaction and oxygen evolution reaction, and a binder-free composite air cathode design is proposed to improve electrochemical performances of zinc-air batteries.2. An ultra-small potential gap of 0.661 V at 10 mA cm-2 (ΔE10) is achieved for the air cathode, and an ultrahigh discharge power density of 365.7 mW cm-2 at a current density of 511.3 mA cm-2 is acquired for the zinc-air battery.

Stable Zn metal anode enabled via ferroelectric nanotube arrays

Aqueous zinc-ion batteries are receiving increasing attention owing to their markedly high safety and low cost. However, the uncontrolled zinc dendrite growth and the side reactions at Zn-electrolyte interfaces hinder the practical application of aqueous rechargeable zinc-based batteries. Therefore, regulating the electrode/electrolyte interface to achieve dense zinc deposition is crucial for improving the electrochemical performance of zinc-ion batteries. Herein, ferroelectric composite nanotube arrays (BaTiO3 modified TiO2 nanotubes, TiO2@BaTiO3) are designed and fabricated as the three-dimensional current collector for Zn metal anode. Abundant zincophilic sites on the surface of BaTiO3 induce zinc nucleation, enabling a compact and horizontally-aligned Zn morphology. At external electric field, the depolarization field produced the ferroelectric BaTiO3 layer on the electrode surface can accelerate the dissociation of ZnSO4 and regulate the Zn-ion desolvation process at the interfaces, leading to dendrite-free Zn deposition and less byproducts. As a result, the TiO2@BaTiO3/Zn anode achieves reversible Zn plating/stripping with low overpotential for over 3000 h at 3 mA cm−2 in symmetric cells, and the assembled full battery exhibits a significantly enhanced cycling stability over 1800 cycles at 1 A g−1. Ferroelectric nanotube arrays brings new opportunities for next-generation aqueous zinc-ion batteries.

Promoting Electrocatalytic Oxygen Reactions Using Advanced Heterostructures for Rechargeable Zinc-Air Battery Applications.

In order to facilitate electrochemical oxygen reactions in electrically rechargeable zinc-air batteries (ZABs), there is a need to develop innovative approaches for efficient oxygen electrocatalysts. Due to their reliability, high energy density, material abundance, and ecofriendliness, rechargeable ZABs hold promise as next-generation energy storage and conversion devices. However, the large-scale application of ZABs is currently hindered by the slow kinetics of the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). However, the development of heterostructure-based electrocatalysts has the potential to surpass the limitations imposed by the intrinsic properties of a single material. This Account begins with an explanation of the configurations of ZABs and the fundamentals of the oxygen electrochemistry of the air electrode. Then, we summarize recent progress with respect to the variety of heterostructures that exploit bifunctional electrocatalytic reactions and overview their impact on ZAB performance. The range of heterointerfacial engineering strategies for improving the ORR/OER and ZAB performance includes tailoring the surface chemistry, dimensionality of catalysts, interfacial charge transfer, mass and charge transport, and morphology. We highlight the multicomponent design approaches that take these features into account to create advanced highly active bifunctional catalysts. Finally, we discuss the challenges and future perspectives on this important topic that aim to enhance the bifunctional activity and performance of zinc-air batteries.

(Invited) Graphene-Supported Fe/Ni Single Atoms and Feni Alloy Nanoparticles as Bifunctional Oxygen Electrocatalysts for Rechargeable Zinc-Air Batteries

To alleviate the severe energy crisis and environmental problems caused by the massive and unsustainable consumption of fossil fuels, it is urgent to develop renewable energy conversion and energy storage technologies to reform the traditional energy structure. Batteries are considered as one of the most promising energy storage technologies due to their sustainability, high efficiency and less pollution. Among various battery storage devices, rechargeable zinc-air batteries (ZABs) have attracted widespread attention on account of their high theoretical energy density (1086 Wh kg– 1), low cost, abundant zinc resources, low operating temperature, and good stability and safety in aqueous environments. However, the kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occurred on the air electrode during the discharging and charging processes are extremely sluggish, leading to low energy efficiency, which significantly limits the large-scale application of rechargeable ZABs. Pt-based electrocatalysts exhibit high ORR activities, while Ru- and Ir-based oxides are excellent OER electrocatalysts, but natural scarcity, high cost and poor durability seriously reduce the marketability and commercial competitiveness of rechargeable ZABs. Therefore, the development of robust, cost-effective and high-efficiency non-noble metal bifunctional ORR/OER electrocatalysts is of crucial significance for the practical application of rechargeable ZABs.As a promising alternative, earth-abundant transition metal (Fe, Co, Ni, etc.)-based materials have been extensively studied due to their relatively high electrocatalytic activity and durability. Thereinto, transition metal and nitrogen co-doped carbon (M-NC), especially Fe-NC, has been demonstrated to be the most effective ORR catalyst, and the active sites are generally considered as atomically dispersed metal coordinated to N atoms (M-Nx sites, x indicates the number of N atoms coordinating the metal). Nevertheless, M-NC catalysts only possess good ORR activity with poor OER performance. Bimetallic FeNi nanocomposites (metals, oxides, carbides, sulfides) are promising for OER. At high potentials, highly active FeNi oxyhydroxide species are generated on the surface of the FeNi-based electrocatalysts. Since ORR and OER depend on different catalytic active sites, an ideal bifunctional oxygen electrocatalysts should integrate M-NC complex with high ORR activity and bimetallic FeNi nanocomposite with a high OER activity to achieve bifunctionality. However, due to the intense competition between transition-metal single atoms and nanocomposites in the preparation process, it is challenging to combine them properly for superior bifunctional ORR/OER catalytic activity.Herein, we report a bifunctional oxygen electrocatalyst consisting of ZIF-derived carbon-anchored Fe/Ni single atoms and FeNi alloy nanoparticles; meanwhile, graphene is also introduced as carbon support to improve the uniformity of active sites (denoted as Fe/Ni-NC||FeNi@G). Benefiting from this unique composition and structure, Fe/Ni-NC||FeNi@G electrocatalyst displays excellent bifunctional ORR/OER activity and durability in rechargeable ZABs. This work provides an effective approach to designing highly efficient non-noble metal multifunctional catalysts for practical applications in rechargeable metal-air batteries. Acknowledgements Thanks for the financial support from the Shenzhen Science and Technology Innovation Committee (JCYJ20180507183818040).

Understanding the NaxMnO2 System: A Thermodynamics and XPS Approach.

The NaxMnO2 system is an important class of materials with potential applications in rechargeable batteries, supercapacitors, catalysts, and gas sensors. This work reports the synthesis of NaxMnO2 (x = 0.39, 0.44, 0.48, 0.66, and 0.70) compounds and their characterization by powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and impedance spectroscopy (IS) techniques. The compounds in this series exhibit a significant variation in their structures with the extent of Na-content. The change in the nature of bonding with increasing Na content was investigated, and its effect on material stability as well as electrotransport properties was investigated. A detailed thermodynamic evaluation of these materials was carried out employing calorimetric techniques, and the data were correlated with changes in the chemical environment around the Na ion. This analysis is crucial for predicting the thermodynamic stability of NaxMnO2 compounds under different environments for their applications in Na-ion batteries.

Self-Assembled Molecular Layers as Interfacial Engineering Nanomaterials in Rechargeable Battery Applications.

Rechargeable batteries have transformed human lives and modern industry, ushering in new technological advancements such as mobile consumer electronics and electric vehicles. However, to fulfill escalating demands, it is crucial to address several critical issues including energy density, production cost, cycle life and durability, temperature sensitivity, and safety concerns is imperative. Recent research has shed light on the intricate relationship between these challenges and the chemical processes occurring at the electrode-electrolyte interface. Consequently, a novel approach has emerged, utilizing self-assembled molecular layers (SAMLs) of meticulously designed molecules as nanomaterials for interface engineering. This research provides a comprehensive overview of recent studies underscoring the significant roles played by SAML in rechargeable battery applications. It discusses the mechanisms and advantageous features arising from the incorporation of SAML. Moreover, it delineates the remaining challenges in SAML-based rechargeable battery research and technology, while also outlining future perspectives.

An ultrathin and robust single-ion conducting interfacial layer for dendrite-free lithium metal batteries

The practical application of rechargeable lithium metal batteries (LMBs) encounters significant challenges due to the notorious dendrite growth triggered by uneven Li deposition behaviors. In this work, a mechanically robust and single-ion-conducting interfacial layer, fulfilled by the strategic integration of flexible cellulose acetate (CA) matrix with rigid graphene oxide (GO) and LiF fillers (termed the CGL layer), is rationally devised to serve as a stabilizer for dendrite-free lithium (Li) metal batteries. The GCL film exhibits favorable mechanical properties with high modulus and flexibility that help to relieve interface fluctuations. More crucially, the electron-donating carbonyl groups (C=O) enriched in GCL foster a strengthened correlation with Li+, which availably aids the Li+ desolvation process and expedites facile Li+ mobility, yielding exceptional Li+ transference number of 0.87. Such single-ion conductive properties regulate rapid and uniform interfacial transport kinetics, mitigating the growth of Li dendrites and the decomposition of electrolytes. Consequently, stable Li anode with prolonged cycle stabilities and flat deposition morphologies are realized. The Li||LiFePO4 full cells with CGL protective layer render an outstanding cycling capability of 500 cycles at 3 C, and an ultrahigh capacity retention of 99.99% for over 220 cycles even under harsh conditions. This work affords valuable insights into the interfacial regulation for achieving high-performance LMBs.

Coal-based carbon nanosheets contained carbon microfibers modified with grown carbon nanotubes as efficient air electrode material for rechargeable zinc-air batteries

Coal-based oxygen electrocatalysts hold immense promise for cost-effective applications in rechargeable Zn-air batteries (ZABs) and the value-added, clean utilization of traditional coal resources. Herein, an electrospun membrane electrode comprising coal-derived carbon nanosheets and directly grown carbon nanotubes (CNS/CMF@CNT) was successfully synthesized. The hierarchical porous structure of the electrode, composed of multiple components, significantly facilitates mass and ion transportation, resulting in exceptional electrochemical performance. Employing Fe as the catalyst for CNT growth, the CNS/CMF@CNT electrode exhibits a remarkable onset potential of 0.96 V and a half-wave potential of 0.87 V in the oxygen reduction reaction (ORR). In-situ surface-enhanced Raman spectroscopy reveals that hydroxyl radical desorption on the surface of CNS/CMF@CNT(Fe) is the rate-determining step of the ORR. Notably, the aqueous ZAB featuring the CNS/CMF@CNT(Fe) electrode achieved a peak power density of 216.0 mW cm−2 at a current density of 414 mA cm−2 and maintained a voltage efficiency of 65.1 % after 2000 charge/discharge cycles at 5 mA cm−2. Furthermore, the all-solid-state ZAB incorporating this electrode displayed an open-circuit voltage of 1.43 V, a peak power density of 70.1 mW cm−2 at a current density of 110 mA cm−2, and a voltage efficiency of 66.5 % after 150 charge/discharge cycles. The utilization of abundant coal as the raw material for electrode fabrication not only brings conceivable economic benefits in ZAB construction, but also commendably advances the effective application of traditional coal resources in a more sustainable manner.

A novel layered cobalt oxide Ba2Co9O14 as an efficient and durable bifunctional oxygen electrocatalyst for rechargeable zinc-air batteries

In this work, a layered cobalt oxide Ba2Co9O14 (BCO), belongs to a Ban+1ConO3n+3(Co8O8) family composed by alternating CdI2 based layers (Co8O8) with n (111) perovskite blocks (Ban+1ConO3n+3), has been developed as a potential bifunctional oxygen electrocatalyst candidate for efficient and durable rechargeable zinc-air battery (ZAB) application. Because of the greatly increased the specific surface area caused by ball-milling, the as-milled BCO material exhibits strongly enhanced bifunctional electrocatalytic activity towards oxygen reduction and oxygen evolution reaction in alkaline medium. Moreover, the assembled BCO-based ZAB yields an effectively improved maximum output power density of 166 mW cm−2, a considerable specific capacity of 789 mAh g−1, and excellent charge-discharge cycle stability of over 250 h at 10 mA cm−2 with over 1500 cycles.

High-Entropy Oxides for Rechargeable Batteries.

High-entropy oxides (HEOs) have garnered significant attention within the realm of rechargeable batteries owing to their distinctive advantages, which encompass diverse structural attributes, customizable compositions, entropy-driven stabilization effects, and remarkable superionic conductivity. Despite the brilliance of HEOs in energy conversion and storage applications, there is still lacking a comprehensive review for both entry-level and experienced researchers, which succinctly encapsulates the present status and the challenges inherent to HEOs, spanning structural features, intrinsic properties, prevalent synthetic methodologies, and diversified applications in rechargeable batteries. Within this review, the endeavor is to distill the structural characteristics, ionic conductivity, and entropy stabilization effects, explore the practical applications of HEOs in the realm of rechargeable batteries (lithium-ion, sodium-ion, and lithium-sulfur batteries), including anode and cathode materials, electrolytes, and electrocatalysts. The review seeks to furnish an overview of the evolving landscape of HEOs-based cell component materials, shedding light on the progress made and the hurdles encountered, as well as serving as the guidance for HEOs compositions design and optimization strategy to enhance the reversible structural stability, electrical properties, and electrochemical performance of rechargeable batteries in the realm of energy storage and conversion.

Electron redistribution and proton transfer induced by atomically fully exposed Cu-O-Fe clusters coupled with single-atom sites for efficient oxygen electrocatalysis

Single-atom catalysts have garnered significant attention by showing sparkling performance in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the air cathode side of energy devices such as metal-air batteries and fuel cells. This work presents a novel catalyst, AC-CuFe-NC, that incorporates Fe-doped CuO atomic clusters (CuOFe) synergistically with single-atom sites. The AC-CuFe-NC demonstrates outstanding ORR performance (half-wave potential of 0.92 V) and an oxygen overpotential gap between ORR and OER as low as 0.61 V, which is among the top reported performances. Combined with in situ ATR-SEIRAS and DFT calculations, it is shown that the synergistic CuOFe atomic clusters are effective in inducing the electronic structure redistribution of the Fe single-atom site, modulating oxygen adsorption energy, and lowering ORR barriers. More importantly, it is revealed that the synergistic adsorption of clusters and single-atom sites establishes hydrogen bonds between the oxygenated intermediates and the electrolyte H2O molecules. The constructed hydrogen bond can provide a pathway for efficient proton transport as supported by kinetic isotope experiments, leading to a substantial enhancement in reaction kinetics. Additionally, the oxygenated intermediates are stabilized, and the Fe-O bond is elongated during the final step of ORR, thereby facilitating the desorption of OH*. The excellent bifunctional electrocatalytic performance of AC-CuFe-NC enable it to show promising application in rechargeable Zn-air batteries. The innovative catalyst structure and synergistic mechanism demonstrated in this study shed light on the development of high-performance catalysts in energy devices.

Emerging Chemistry for Wide-Temperature Sodium-Ion Batteries.

The shortage of resources such as lithium and cobalt has promoted the development of novel battery systems with low cost, abundance, high performance, and efficient environmental adaptability. Due to the abundance and low cost of sodium, sodium-ion battery chemistry has drawn worldwide attention in energy storage systems. It is widely considered that wide-temperature tolerance sodium-ion batteries (WT-SIBs) can be rapidly developed due to their unique electrochemical and chemical properties. However, WT-SIBs, especially for their electrode materials and electrolyte systems, still face various challenges in harsh-temperature conditions. In this review, we focus on the achievements, failure mechanisms, fundamental chemistry, and scientific challenges of WT-SIBs. The insights of their design principles, current research, and safety issues are presented. Moreover, the possible future research directions on the battery materials for WT-SIBs are deeply discussed. Progress toward a comprehensive understanding of the emerging chemistry for WT-SIBs comprehensively discussed in this review will accelerate the practical applications of wide-temperature tolerance rechargeable batteries.

Synthesis and electrochemical studies of 1,1’-binaphthyl-2,2’-diol for aqueous rechargeable lithium-ion battery applications

The constant increase in the utilization of lithium-ion batteries (LIBs) in various field applications, including electrical vehicles and electronic devices, has led researchers to focus on their multiple path developments to obtain new electrode materials. The practical development of these electrode materials, based on organic and inorganic moieties, is challenging for various groups of LIB scientists. The concept of organic electrode materials is highly competitive with inorganic electrode materials because of the accessibility of more active sites with structural diversity, high energy and power density, environmental friendliness potential sustainability, and low cost. Herein, 1,1’-binaphthyl-2,2’-diol (BINOL) is investigated as an organic electrode material that contains two hydroxyl groups that act as active centers. The oxidative coupling process is employed to synthesize BINOL and so obtained product was characterized by using FT-IR, 1H-NMR and MASS techniques. The electrochemical investigations were carried out using sat. Li2SO4 electrolytic medium at three-electrode cell system. The Cyclic voltammetry (CV) has provided information on the anodic behavior of the material and its stability studied at different scan rates. The battery performance of the cell BINOL | Sat. Li2SO4 | LiMn2O4 by galvanostatic charge-discharge potential limit (GCPL) shows 197/171mAhg−1 specific capacity and 90% columbic efficiency. The electrochemical kinetic obtained by potentiostatic electrochemical impedance spectroscopy (PEIS) shows a semi-infinite diffusion process.

Releasing Free Anions by High Donor Number Cosolvent in Noncorrosive Electrolytes of Commercially Available Magnesium Salts.

Passivation of the magnesium (Mg) anode in the chloride-free electrolytes using commercially available Mg salts is a critical issue for rechargeable Mg batteries. Herein, a high donor number cosolvent of 1-methylimidazolium (MeIm) is introduced into Mg(TFSI)2- and Mg(HMDS)2-based electrolytes to address the passivation problem and realize highly reversible Mg plating/stripping. Theoretical calculations and experimental characterization results reveal that the strong coordination ability of MeIm with Mg2+ can weaken the anion-cation interactions and promote the formation of free anions that have higher reduction stability, thus significantly suppressing anion-derived passivation layer formation. By adding MeIm cosolvent into Mg(TFSI)2-based electrolyte, the average Coulombic efficiency of the Mg//Cu cell is increased from less than 20% to over 90%, and the Mg//Mg cell can stably cycle for over 800 h with a low overpotential. In the MeIm-regulated Mg(HMDS)2-based electrolyte, the solvation structure change, featured by an effective separation of Mg2+ and HMDS-, greatly increases the ionic conductivity by more than 30 times. This solvation structure regulation strategy for noncorrosive electrolytes of commercially available Mg salts has a great potential for application in future rechargeable Mg metal batteries.

Achieving Long-Cycle-Life Zinc-Ion Batteries through a Zincophilic Prussian Blue Analogue Interphase.

The practical application of rechargeable aqueous zinc-ion batteries (ZIBs) has been severely hindered by detrimental dendrite growth, uncontrollable hydrogen evolution, and unfavorable side reactions occurring at the Zn metal anode. Here, we applied a Prussian blue analogue (PBA) material K2Zn3(Fe(CN)6)2 as an artificial solid electrolyte interphase (SEI), by which the plentiful -C≡N- ligands at the surface and the large channels in the open framework structure can operate as a highly zincophilic moderator and ion sieve, inducing fast and uniform nucleation and deposition of Zn. Additionally, the dense interface effectively prevents water molecules from approaching the Zn surface, thereby inhibiting the hydrogen-evolution-resultant side reactions and corrosion. The highly reversible Zn plating/stripping is evidenced by an elevated Coulombic efficiency of 99.87% over 600 cycles in a Zn/Cu cell and a prolonged lifetime of 860 h at 5 mA cm-2, 2 mAh cm-2 in a Zn/Zn symmetric cell. Furthermore, the PBA-coated Zn anode ensures the excellent rate and cycling performance of an α-MnO2/Zn full cell. This work provides a simple and effective solution for the improvement of the Zn anode, advancing the commercialization of aqueous ZIBs.

Low-Overpotential Rechargeable Na-CO2 Batteries Enabled by an Oxygen-Vacancy-Rich Cobalt Oxide Catalyst.

Rechargeable sodium-carbon dioxide (Na-CO2) batteries have been proposed as a promising CO2 utilization technique, which could realize CO2 reduction and generate electricity at the same time. They suffer, however, from several daunting problems, including sluggish CO2 reduction and evolution kinetics, large polarization, and poor cycling stability. In this study, a rambutan-like Co3O4 hollow sphere catalyst with abundant oxygen vacancies was synthesized and employed as an air cathode for Na-CO2 batteries. Density functional theory calculations reveal that the abundant oxygen vacancies on Co3O4 possess superior CO2 binding capability, accelerating CO2 electroreduction, and thereby improving the discharge capacity. In addition, the oxygen vacancies also contribute to decrease the CO2 decomposition free energy barrier, which is beneficial for reducing the overpotential further and improving round-trip efficiency. Benefiting from the excellent catalytic ability of rambutan-like Co3O4 hollow spheres with abundant oxygen vacancies, the fabricated Na-CO2 batteries exhibit extraordinary electrochemical performance with a large discharge capacity of 8371.3 mA h g-1, a small overpotential of 1.53 V at a current density of 50 mA g-1, and good cycling stability over 85 cycles. These results provide new insights into the rational design of air cathode catalysts to accelerate practical applications of rechargeable Na-CO2 batteries and potentially Na-air batteries.