Fabio Maroni

This review paper aims at addressing the status of transition metal‐based cathode materials for Mg 2+ and Ca 2+ ‐based multivalent ion batteries on a critical standpoint, providing a comprehensive overview. Multivalent‐based ions battery (MIB) technologies are among the most promising post‐Lithium electrochemical energy storage devices currently studied, but still they fall short in several aspects due to their early stage of research. In addition, difficult experimental conditions related to the electrolyte systems and the cathode materials require an additional quote of care when performing experiments. In this review, a global approach is undertaken, from an introduction to electrolytes to the studied insertion parameters that allow a fast (de)insertion of multivalent ions. Then the currently studied structural classes of cathode materials and a critic comment on data reporting, which are among the focal points of the actual state‐of‐the‐art research, are thoroughly discussed.

Mn dissolution is the main drawback of LiMn 2 O 4 cathodes, leading to capacity fading and anode poisoning. It is well known that improved capacity/cycling performances have been obtained by the Al 2 O 3 coating. It is less clear what is the effect of the coating from the point of view of the fundamental processes occurring within the active material and on the interface with the active material, especially during the first cycle, when a dynamical interaction at a high voltage with an electrolyte and a binder leads to the formation of a passivation layer. We present here the close comparison of coated and uncoated electrodes' X-ray absorption analysis at the interface during the measurements of several charged/discharged states of the electrode. The Al 2 O 3 coating is significantly effective for stopping the high voltage instability of the battery, especially, when the Mn−O couple reacts with organic species, limiting Mn capture and the electrolyte reaction with the oxide surface. In the low-voltage discharge, on the other hand, more complex structure/electronic modifications occur. The presence of the coating limits disproportionation, preventing a general corrosion with dissolution of the Mn 2+ species, and hence improves the electrode performance. From the structural point of view, the signatures of the transformations and a reversible modification of the surface character of the nanoparticles from a spinel to a defective phase are observed, while no charge transfer between the coating and manganese oxide is found. The role of nonthermodynamic interphase formation by means of proton transfer is enhanced for the coated oxide particles.

The increase in energy density of the next generation of battery materials to meet the new challenges of the electrical vehicles era calls for innovative and easily scalable materials with sustainable processes. An innovative Cu x O/C nanocomposite material, characterized by a highly conductive 3D-framework, with Cu x O/Cu-metal contiguous nanodomains is prepared by electrospinning. The electrode processing is made using a polyacrylic acid binder. The nanocomposite has been fully characterized and the electrochemical performance shows high specific capacity values over 450 galvanostatic cycles at 500 mAg À 1 specific current with capacity retention values over 80 %. In addition, the composite shows remarkable high rate performance and highly stable interface, which has been studied by impedance spectroscopy.

This paper reports the performance comparison between the exhaustive and equilibrium extraction using classical Avantor C18 solid phase extraction (SPE) sorbent, hydrophilic-lipophilic balance (HLB) SPE sorbent, Sep-Pak C18 SPE sorbent, novel sol-gel Carbowax 20M (sol-gel CW 20M) SPE sorbent, and sol-gel CW 20M coated fabric phase sorptive extraction (FPSE) media for the simultaneous extraction and analysis of three inflammatory bowel disease (IBD) drugs that possess logP values (polarity) ranging from 1.66 for cortisone, 2.30 for ciprofloxacin, and 2.92 for sulfasalazine. Both the commercial SPE phases and in-house synthesized sol-gel CW 20M SPE phases were loaded in SPE cartridges and the extractions were carried out under an exhaustive extraction mode. FPSE was carried out under an equilibrium extraction mode. The drug compounds were resolved using a Luna C18 column (250 mm × 4.6 mm; 5 m particle size) in gradient elution mode within 20 min and the method was validated in compliance with international guidelines for the bioanalytical method validation. Novel in-house synthesized and loaded sol-gel CW 20M SPE sorbent cartridges were characterized in terms of their extraction capability, breakthrough volume, retention volume, holdup volume, number of the theoretical plate, and the retention factor.

Vanadium oxide gels are appealing cathode materials as they offer multiple electron redox processes leading to high cation‐storage capacities. Moreover, they are able to intercalate different ionic and molecular species. Apart from low electronic conductivity, one of the main factors hindering the use of highly porous V2O5 gels is the difficulty in preserving their unique morphology, made up of an entangled network of thin ribbons, during conventional laminated electrode preparation. In this study, we tune the V2O5 synthesis conditions and use an innovative and green binder system (polyacrylic acid and ethanol) to obtain electrodes with a morphology optimized for ion intercalation. The electrochemical performance of such electrodes, tested against lithium and sodium anodes, are shown to be excellent.

Conversion‐enabled transition metal oxides are mostly characterized by environmental benignity, low cost, and high theoretical capacities, which make them suitable as candidate anode materials for Li‐ion batteries. To ensure high efficiency and stability, the use of novel and tailored morphologies is recommended. Among the other methods, the use of natural extracts as templates is one of the possible strategies to accomplish this task. In this work, Fe2O3 nanoparticles are synthesized by using vanillin as a soft templating agent, and fully characterized on a morphological, structural and electrochemical level. Poly(acrylic acid) binder and ethanol for electrode preparation ensure a fully environmentally benign process from synthesis to electrode testing. The cells deliver capacity values up to 700 mAh g−1 under prolonged galvanostatic cycling at 500 mA g−1, as well as excellent rate capability and high efficiency.

A tin-decorated reduced graphene oxide, originally developed for lithium-ion batteries, has been investigated as an anode in sodium-ion batteries. The composite has been synthetized through microwave reduction of poly acrylic acid functionalized graphene oxide and a tin oxide organic precursor. The final product morphology reveals a composite in which Sn and SnO 2 nanoparticles are homogenously distributed into the reduced graphene oxide matrix. The XRD confirms the initial simultaneous presence of Sn and SnO 2 particles. SnRGO electrodes, prepared using Super-P carbon as conducting additive and Pattex PL50 as aqueous binder, were investigated in a sodium metal cell. The Sn-RGO showed a high irreversible first cycle capacity: only 52% of the first cycle discharge capacity was recovered in the following charge cycle. After three cycles, a stable SEI layer was developed and the cell began to work reversibly: the practical reversible capability of the material was 170 mA·h·g −1. Subsequently, a material of formula NaLi 0.2 Ni 0.25 Mn 0.75 O δ was synthesized by solid-state chemistry. It was found that the cathode showed a high degree of crystallization with hexagonal P2-structure, space group P6 3 /mmc. The material was electrochemically characterized in sodium cell: the discharge-specific capacity increased with cycling, reaching at the end of the fifth cycle a capacity of 82 mA·h·g −1. After testing as a secondary cathode in a sodium metal cell, NaLi 0.2 Ni 0.25 Mn 0.75 O δ was coupled with SnRGO anode to form a sodium-ion cell. The electrochemical characterization allowed confirmation that the battery was able to reversibly cycle sodium ions. The cell's power response was evaluated by discharging the SIB at different rates. At the lower discharge rate, the anode capacity approached the rated value (170 mA·h·g −1). By increasing the discharge current, the capacity decreased but the decline was not so pronounced: the anode discharged about 80% of the rated capacity at 1 C rate and more than 50% at 5 C rate.