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Potentials derived with machine learning algorithms achieve the accuracy of high-fidelity quantum mechanical computations such as density functional theory (DFT), while allowing orders of magnitude lower computational time. In this work, we demonstrate the use of uncertainty aware equivariant graph neural networks for predicting spin-resolved electron densities, forces, and energies of the Na3V2(PO4)3 NASICON structured cathode. Due to the speedup in computational time, we are able to investigate structures of ∼300 atoms for 200 million timesteps. The ability to model larger systems on the nanosecond length scale with maintaining DFT level accuracy allowed critical insights into the diffusion characteristics of Na-ions, associated electron transfer processes, and dependence of diffusivity on sodium concentration in the structure.

Gel polymer electrolytes composed of deep eutectic solvent Acetamide4:Zn(TFSI)2 and poly(ethylene oxide) (PEO) are prepared using a fast, solvent-free procedure. The effect of the PEO molecular weight and its concentration on the physicochemical and electrochemical properties of the electrolytes are studied. Gels prepared with ultra-high molecular weight PEO present pseudo-solid behavior and ionic conductivity even higher than that of the original liquid electrolyte. A decrease in the dendritic growth in soft gels with PEO contents up to 1 wt. % is demonstrated. The changes in the chemical structure of the electrolyte produced by the strong interactions between ethylene oxide units and Zn2+ have also been studied. The addition of PEO takes the electrolyte out of its original eutectic composition, producing blend crystallization. However, it is possible to retain the eutectic point of the electrolyte in a gel form if the addition of PEO is accompanied by the reduction of acetamide.

Rechargeable magnesium batteries are promising energy storage technology which could eventually power electric cars. However, the double charge of Mg-ion results in sluggish kinetics in most cathode materials. Due to that, exotic materials, with more complex discharging mechanisms than what we are used for conventional Li-ion batteries, have been explored. In particular, vanadium tetrasulfide (VS4), a quasi-1D material, was recently shown to be a good candidate for magnesium storage, providing good theoretical capacity and excellent kinetics for magnesium intercalation. Here we present a DFT-based analysis of the complex magnesation process of VS4. The results indicate a mixed hetero- and homogeneous process with Mg0.75VS4 formed at the initial stages of the cathode discharge. At higher magnesiation levels (i.e., MgxVS4 with x > 1) we observed a possible degradation mechanism related to the V[sbnd]S bond breaking, which leads to the formation of magnesium sulfur clusters inside the structure. All of that enables us to identify the origin of the superior properties of VS4 as cathode material, enabling the design of strategies to further improve its performance.

Driven by the continuous search for improving performances, understanding the phenomena at the electrode/electrolyte interfaces has become an overriding factor for the success of sustainable and efficient battery technologies for mobile and stationary applications. Toward this goal, rapid advances have been made regarding simulations/modeling techniques and characterization approaches, including high-throughput electrochemical measurements coupled with spectroscopies. Focusing on Li-ion batteries, current developments are analyzed in the field as well as future challenges in order to gain a full description of interfacial processes across multiple length/timescales; from charge transfer to migration/diffusion properties and interphases formation, up to and including their stability over the entire battery lifetime. For such complex and interrelated phenomena, developing a unified workflow intimately combining the ensemble of these techniques will be critical to unlocking their full investigative potential. For this paradigm shift in battery design to become reality, it necessitates the implementation of research standards and protocols, underlining the importance of a concerted approach across the community. With this in mind, major collaborative initiatives gathering complementary strengths and skills will be fundamental if societal and environmental imperatives in this domain are to be met.

Magnesium batteries are one of the most promising post-lithium technologies. One of the main challenges preventing its commercialization is to find an efficient and safe electrolyte. The electrolyte, playing the role of the blood in a battery, interacts with all battery components and must be highly compatible with all of them. The development of Cl-free electrolyte systems is desired to avoid corrosion issues, and many studies suggest magnesium tetrakis(hexafluoroisopropyloxy)borate (Mg[B(hfip)4]2) as one of the best candidates in terms of electrochemical properties and chemical stability. Here we present an in-depth analysis of the unique structure of this salt and the interactions generated in the electrolyte among the dissociated ions. The results show a delicate balance between electron-withdrawing effects and ligand stabilization in B(hfip)4−, crucial from the point of view of magnesium electrolytes. Moreover, the bulk nature of B(hfip)4− limits the anion-cation contacts to infrequent interactions through fluorine atoms. This has consequences not only for ion transport but also for hindering the anion decomposition towards the formation of MgF2. Taken together, we managed to demystify the exclusive nature of B(hfip)4− anion, thereby allowing for further rational development of new anion structures.