Preparation and electrochemical characterization of TiO2 as an anode material for magnesium-ion batteries

Anode on the basis of titanium dioxide powder was made. Its morphological characteristics were investigated using ellipsometry, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Electrochemical properties were also investigated by cyclic voltammetry. Dispersing, mixing the initial reagents for obtaining homogenized paste and its coating to a substrate, drying and cutting the electrodes were main steps of anode production. The results of ellipsometry, SEM and EDS demonstrated a uniformly distributed layer of about 200 μm thickness with porous structure, particle diameter of 50–80 nm and titanium dioxide content (45.7 %). The XRD data confirmed the active anode matrix formation with a monoclinic crystal lattice corresponding to the modification of titanium dioxide (B) with small anatase inclusions. Electrochemical behavior of the electrode was examined in acetonitrile-based Mg(TFSI)2 solution. Diffusion coefficient (DMg) and the charge transfer rate constant (kct) were determined from cyclic voltammograms 1.54∙10–2 cm2/s and 1.29∙10–4 cm/s, respectively. A two-step electrochemical reaction was revealed by the ratio of the electricity amount consumed in the cathode and anode processes at varying the number of cycles. Small values of polarization resistance (Rp) calculated from cyclic voltammograms indicated rapid diffusion of magnesium ions during intercalation/deintercalation.

Communication—Lithium Titanate as Mg-Ion Insertion Anode for Mg-Ion Sulfur Batteries Based on Sulfurated Poly(acrylonitrile) Composite

Spinel lithium-titanate Li4Ti5O12 (LTO) is a promising anode material for magnesium batteries due to its non-toxicity, low-cost, zero-strain characteristics and long-term stability. Nevertheless, the application of LTO in a magnesium full cell has been rarely investigated. Herein, we give a proof of concept for the feasibility of LTO as anode in full magnesium ion batteries, which might prevent the passivation of metallic Mg anodes. Mg2+ was electrochemically inserted into LTO prior to cycling against a sulfur-based cathode material, i.e. sulfurated poly(acrylonitrile), SPAN, resulting in stable cycle performance with 800 mAh/gS at 0.3C and high-rate capability.

Unveiling the Magnesium Storage Mechanisms of Co-Sputtered Indium-Tin Alloy Films Using Operando X-ray Diffraction

Tin (Sn)-based anodes have drawn extensive attention for magnesium ion batteries (MIBs) owing to their low reaction potentials, high theoretical capacities, and compatibility with conventional electrolytes. However, their poor electrochemical reactivity, sluggish kinetics, and large volume changes have obstructed progresses. Additionally, a clear understanding of the Mg storage chemistry is crucial for the development of high-performance MIBs. Here, we prepared self-supporting In-Sn alloy films with different compositions and phase constitutions via a one-step magnetron co-sputtering. As benchmarked with pure Sn film, the single-phase and biphase In-Sn alloy films effectively trigger the alloying reaction of Sn with Mg and further increasing of In significantly improves the electrochemical reactivity of the In-Sn electrodes. More importantly, operando X-ray diffraction was performed to unveil the magnesiation/demagnesiation mechanisms of the In0.2Sn0.8, In0.2Sn0.8/In3Sn and In3Sn electrodes, showing that In0.2Sn0.8 and In3Sn display different Mg storage mechanisms when existing alone or biphase coexisting. Our findings highlight the significance of the electrode design and mechanism investigations for MIBs.

The Evaluation of Mg-Ga Compounds as Electrode Materials for Mg-Ion Batteries via Ab Initio Simulation

The Mg-Ga alloy-type electrode is one of the potential anode materials for Magnesium-ion batteries (MIBs). In this work, the thermodynamic, electrochemical and kinetic properties of Mg-Ga compounds, i.e. Mg2Ga5, MgGa2, MgGa, Mg2Ga and Mg5Ga2, have been systematically studied. Combining the first-principles calculations and charge-discharge experimental results, the structure evolution and voltage curves of Mg-Ga compounds are presented, where the Mg-Ga compounds show low voltages and high capacity up to 1922 mAh·g-1 with Mg5Ga2. Additionally, the diffusion barriers of Mg in Mg-Ga alloys are low, which is favorable for the fast ion-transmission and then good rate performance as anodes of MIBs.