Divalent Nonaqueous Metal-Air Batteries

Abstract

In the field of secondary batteries, the growing diversity of possible applications for energy storage has led to the investigation of numerous alternative systems to the state-of-the-art lithium-ion battery. Metal-air batteries are one such technology, due to promising specific energies that could reach beyond the theoretical maximum of lithium-ion. Much focus over the past decade has been on lithium and sodium-air, and, only in recent years, efforts have been stepped up in the study of divalent metal-air batteries. Within this article, the opportunities, progress, and challenges in nonaqueous rechargeable magnesium and calcium-air batteries will be examined and critically reviewed. In particular, attention will be focused on the electrolyte development for reversible metal deposition and the positive electrode chemistries (frequently referred to as the “air cathode”). Synergies between two cell chemistries will be described, along with the present impediments required to be overcome. Scientific advances in understanding fundamental cell (electro)chemistry and electrolyte development are crucial to surmount these barriers in order to edge these technologies toward practical application.

Divalent closo-monocarborane solvates for solid-state ionic conductors

“…Comparatively, a pure lithium metal anode has the highest gravimetric capacity, however, practical use has been limited due to irregular lithium plating during cycling processes causing severe dendrite growth, which consequently can lead to short circuiting of the cell. 7 In comparison, metals like magnesium and calcium are less prone to dendrite growth, as well as having the added benefit of being some of the most abundant elements on earth, and consequently, less expensive and more accessible than lithium. [7][8][9] Calcium and magnesium have similar reduction potentials to lithium for a single-electron transfer, however, as these compounds form divalent cations (M -M 2+ + 2e À ), this doubles the theoretical gravimetric energy capacity of the pure metal anode.…”

Development of a Mg/O ReaxFF Potential to describe the Passivation Processes in Magnesium‐Ion Batteries**

“…The future goal is to extend the presented force field by Mg/H and Mg/C parameters to obtain a full magnesium electrolyte description to model the initial steps of SEI formation in Mg batteries. For the moment, our trained force field offers the opportunity to study the passivation and oxidation of metallic Mg in more detail or to investigate the ongoing reactions in Mg‐air batteries [50–52] …”

Organo-metallic electrolyte additive for regulating hydrogen evolution and self-discharge in Mg–air aqueous battery

“…1, where the solid electrolyte interphase (SEI) layer between the anode and electrolyte plays a vital role in reducing the anode degradation and increasing the charge transport within the electrolyte. 10 Besides, the parasitic corrosion at the electrode–electrolyte interface leads to excessive consumption of hydroxyl ions by the electrode, restricting the practical OCV within 1.4–2.1 V. 11 Maintaining electrolyte stability and ideal ionic conductance has been a long-term issue. One of the uncomplicated strategies is to formulate the electrolytes and increase the salt concentration in suitable solvents.…”