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Herein, we describe the synthesis and evaluation of hierarchical mesoporous orthorhombic niobium oxide (T-Nb2O5) as an anode material for rechargeable lithium-ion batteries (LIB). The as-synthesized material addresses key challenges such as beneficial porous structure, poor rate capability, and cycling performance of the anode for Li-ion devices. The physicochemical characterization results reveal hierarchical porous nanostructure morphology with agglomerated particles and a 20 to 25 nm dimension range. Moreover, the sample has a high specific surface area (~65 m2 g−1) and pore volume (0.135 cm3 g−1). As for the application in Li-ion devices, the T-Nb2O5 delivered an initial discharging capacity as high as 225 mAh g−1 at 0.1 A g−1 and higher rate capability as well as remarkable cycling features (~70% capacity retention after 300 cycles at 250 mA g−1) with 98% average Coulombic efficiency (CE). Furthermore, the scan rate-dependent charge storage mechanism of the T-Nb2O5 electrode material was described, and the findings demonstrate that the electrode shows an evident and highly effective pseudocapacitive Li intercalation behaviour, which is crucial for understanding the electrode process kinetics. The origin of the improved performance of T-Nb2O5 results from the high surface area and mesoporous structure of the nanoparticles. [ABSTRACT FROM AUTHOR]

The rechargeable zinc–air battery is a clean technology for energy storage applications but is impeded by the slow kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during its cycling. Herein, a series of lanthanum cobaltate based perovskites are synthesised with the B-site cation deficiencies in the structure occupied by Ru substitution: LaCo1−xRuxO3−δ (x = 0, 0.1, 0.2, 0.3 and 0.5). These compositions were designed to enhance the OER/ORR activities, which are two vital reactions for rechargeable Zn–air batteries. Powder X-ray diffraction analysis revealed that increasing the Ru substitution >20% (x > 0.2) alters the LaCoO3 crystal structure from rhombohedral to orthorhombic. Photoelectron spectroscopy studies reveal that the surface oxygen vacancies increased in the Ru substituted catalyst, a property important for enhancing the OER/ORR efficiency. The LaCo0.8Ru0.2O3−δ (LCRO82) catalyst exhibits promising electrocatalytic activities in both the OER and the ORR in 0.1 M KOH solution. Furthermore, the LCRO82 catalyst was evaluated as a cathode for rechargeable Zn–air battery applications displaying a high power density of 136 mW cm−2 at a current density of 175 mA cm−2 and a stable charge–discharge voltage gap of 0.78 V after 1440 cycles, with excellent cycling stability over 240 h. [ABSTRACT FROM AUTHOR]

With an anticipation of their use in electric vehicles, Li–O2 batteries are found to be attractive despite their complex chemistry and drawbacks. To be successful, cathode materials that are robust enough to overcome the sluggish kinetics of the charge–discharge reactions are essential. This work reports sonochemically synthesized porous MnCo2O4/graphene (MCO/G) as a hybrid cathode material in nonaqueous Li–O2 batteries. The MCO/G hybrid is synthesized in less than four hours and offers a strong synergistic coupling between the MnCo2O4 nanospheres and graphene sheets. It catalyzes the oxygen reduction through a three‐electron‐transfer process and initiates the oxygen evolution at 1.55 V vs. RHE in basic medium. A small charge–discharge voltage hysteresis of 0.8 V and a cycle life of 250 cycles at a limited capacity of 1000 mAh g−1 in a tetraglyme‐based nonaqueous Li–O2 battery is demonstrated. The porous channels created on the sonochemically synthesized cathode facilitates easy oxygen adsorption onto the active sites to accommodate more discharge products following its decomposition. It exhibits a better rate capability in comparison to the widely used Vulcan carbon and benchmark Pt/C catalysts. The excellent cyclability, rate capability, and low overpotential demonstrates MnCo2O4/graphene composite as a promising cathode candidate for Li–O2 batteries. The porous nanosphere architecture with internal oxygen diffusion pathways and peripheral conductive graphene extensions fulfils the requirements that a robust cathode is expected to have to overcome the harsh Li–O2 battery conditions and to serve as a high‐rate‐capable cathode for Li–O2 batteries. A highly porous MnCo2O4/graphene (MCO/G) hybrid with internal oxygen diffusion pathways has been developed by a sonochemical method. The porous channels throughout the bulk of the MCO nanospheres provide the added surface area that is required to attain the larger capacity. The MCO/G hybrid facilitates the reversible formation of Li oxides at lower overpotentials and higher rates in comparison to Pt/C and Vulcan carbon (see figure). [ABSTRACT FROM AUTHOR]

Chloride–ion batteries (CIBs) offer a compelling alternative to conventional battery systems, particularly in applications demanding cost‐effectiveness and resource sustainability. However, the development of tailored electrode materials remains a critical bottleneck for CIB advancement. In this study, an untapped class of perovskite‐based material, potassium hexachlorostannate (K2SnCl6, denoted as KSC) is synthesized via a facile mechanochemical route for the first time. The prepared KSC is subjected to various characterization techniques to confirm its crystal structure and morphology. Herein, KSC exhibits intriguing electrochemical performance in a non‐aqueous CIB configuration, utilizing a lithium metal counter electrode. Furthermore, ex situ X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) analysis, reveal a conversion reaction mechanism involving chloride ion shuttling and provide insights into structural evolution during cycling. Moreover, the density functional theory (DFT) studies support additional degradation products that can potentially limit the performance of these materials as potential battery electrodes in CIBs. [ABSTRACT FROM AUTHOR]

In P2-type layered oxide cathodes, Na site-regulation strategies are proposed to modulate the Na + distribution and structural stability. However, their impact on the oxygen redox reactions remains poorly understood. Herein, the incorporation of K + in the Na layer of Na 0.67 Ni 0.11 Cu 0.22 Mn 0.67 O 2 is successfully applied. The effects of partial substitution of Na + with K + on electrochemical properties, structural stability, and oxygen redox reactions have been extensively studied. Improved Na + diffusion kinetics of the cathode is observed from galvanostatic intermittent titration technique (GITT) and rate performance. The valence states and local structural environment of the transition metals (TMs) are elucidated via operando synchrotron X-ray absorption spectroscopy (XAS). It is revealed that the TMO 2 slabs tend to be strengthened by K-doping, which efficiently facilitates reversible local structural change. Operando X-ray diffraction (XRD) further confirms more reversible phase changes during the charge/discharge for the cathode after K-doping. Density functional theory (DFT) calculations suggest that oxygen redox reaction in Na 0.62 K 0.03 Ni 0.11 Cu 0.22 Mn 0.67 O 2 cathode has been remarkably suppressed as the nonbonding O 2p states shift down in the energy. This is further corroborated experimentally by resonant inelastic X-ray scattering (RIXS) spectroscopy, ultimately proving the role of K + incorporated in the Na layer., (© 2024 The Author(s). Small published by Wiley‐VCH GmbH.)

Calcium (Ca) batteries represent an attractive option for electrochemical energy storage due to physicochemical and economic reasons. The standard reduction potential of Ca (-2.87 V) is close to Li and promises a wide voltage window for Ca full batteries, while the high abundance of Ca in the earth's crust implicates low material costs. However, the development of Ca batteries is currently hindered by technical issues such as the lack of compatible electrolytes for reversible Ca 2+ plating/stripping and high-capacity cathodes with fast kinetics. Herein, we employed FeS 2 as a conversion cathode material and combined it with a Li + /Ca 2+ hybrid electrolyte for Ca batteries. We demonstrate that Li + ions ensured reversible Ca 2+ plating/stripping on the Ca metal anode with a small overpotential. At the same time, they enable the conversion of FeS 2 , offering high discharge capacity. As a result, the Ca/FeS 2 cell demonstrated an excellent long-term cycling performance with a high discharge capacity of 303 mAh g -1 over 200 cycles. Even though the practical application of such an approach is questionable due to the high quantity of electrolytes, we believe that our scientific findings still provide new directions for studying Ca batteries with long-term cycling.

In the loop of numerous challenges and ambiguities, Li-O 2 batteries are crawling to reach their commercialization phase. To achieve the progressive milestones, along with the developments in the architecture of cathodes, anodes, and electrolytes, understanding its failure mode is equally important. Under an unrestricted charge-discharge protocol, cyclability of nonaqueous Li-O 2 batteries are limited to only a few cycles. This report examines an additive-free ether-based Li-O 2 battery in the perspective of identifying the origin of possible side reactions and their affiliations to integral components of the battery. Structural and compositional changes during every charge-discharge sequence are studied using bottom-up sequential tear-down analysis. The substantial increase in impedance and corresponding decrease in capacities after every cycle are interrelated to the amount of electrode passivation resulting from the discharge products and electrolyte decomposition. From the tear-down analysis, it is approximated that, among the total capacity loss, ≈55% is attributed to the cathode, ≈28% of the loss corresponds to the anode, and ≈17% is attributed to the electrolyte, given that battery failure instigates from the "reactive oxygen species". Electrochemically formed Li 2 O 2 via the superoxide pathway induces large decomposition overpotentials up to 4.6 V versus Li/Li + because of its overrated reactivity with electrolytes and carbon supports. On the contrary, efficient decomposition of chemically formed Li 2 O 2 below 3.9 V proves that the extra charge potential observed for electrochemically formed Li 2 O 2 is in fact consumed for the decomposition of irreversibly formed side products via the superoxide pathway. Spontaneous reactivity of Li 2 O 2 and trivial reactivity of Li 2 O highlight the need of advanced strategies to maneuver oxygen red-ox in selective pathways that unalter the electrolyte and electrodes, and the necessity of their synchronized performance for the evolution of practical Li-O 2 batteries.

Rechargeable zinc-air batteries are considered to be more sustainable and efficient candidates for safe, low-cost energy storage because of their higher energy density and the abundance of zinc resources. Recently Zn-air batteries have aroused significant research attention, however, because an unresolved impediment due to the notorious instability of the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) kinetics of the cathode catalyst limit their practical application. Herein, we report the synthesis of non-precious MnCo 2 O 4 nanospheres synergized with a graphene sheet as a bi-functional cathode catalyst for rechargeable Zn-air battery application using a one-pot probe sonochemical method. Structural characterization confirms that the MnCo 2 O 4 nanospheres successfully anchored on graphene sheet. X-ray photoelectron spectroscopy revealed that the Mn and Co in the MnCo 2 O 4 are in mixed valence states on the graphene sheet surface and the MnCo 2 O 4 -graphene sheet (MCO-GS) hybrid catalyst exhibits excellent OER and ORR activity compared with their individual counterparts. A rechargeable Zn-air battery using an MCO-GS catalyst reveals unique small charge-discharge overpotential, cycling stability and higher rate capability than a bare MnCo 2 O 4 (MCO) catalyst. This superiority in electrocatalytic activity combined with simplicity of material synthesis, turn the MCO-GS hybrid into a promising catalyst for a rechargeable Zn-air battery., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

With an anticipation of their use in electric vehicles, Li-O 2 batteries are found to be attractive despite their complex chemistry and drawbacks. To be successful, cathode materials that are robust enough to overcome the sluggish kinetics of the charge-discharge reactions are essential. This work reports sonochemically synthesized porous MnCo 2 O 4 /graphene (MCO/G) as a hybrid cathode material in nonaqueous Li-O 2 batteries. The MCO/G hybrid is synthesized in less than four hours and offers a strong synergistic coupling between the MnCo 2 O 4 nanospheres and graphene sheets. It catalyzes the oxygen reduction through a three-electron-transfer process and initiates the oxygen evolution at 1.55 V vs. RHE in basic medium. A small charge-discharge voltage hysteresis of 0.8 V and a cycle life of 250 cycles at a limited capacity of 1000 mAh g -1 in a tetraglyme-based nonaqueous Li-O 2 battery is demonstrated. The porous channels created on the sonochemically synthesized cathode facilitates easy oxygen adsorption onto the active sites to accommodate more discharge products following its decomposition. It exhibits a better rate capability in comparison to the widely used Vulcan carbon and benchmark Pt/C catalysts. The excellent cyclability, rate capability, and low overpotential demonstrates MnCo 2 O 4 /graphene composite as a promising cathode candidate for Li-O 2 batteries. The porous nanosphere architecture with internal oxygen diffusion pathways and peripheral conductive graphene extensions fulfils the requirements that a robust cathode is expected to have to overcome the harsh Li-O 2 battery conditions and to serve as a high-rate-capable cathode for Li-O 2 batteries., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)