Practical Stability Limits of Magnesium Electrolytes

Abstract

The development of a Mg ion based energy storage system could provide several benefits relative to today's Li-ion batteries, such as improved energy density. The electrolytes for Mg batteries, which are typically designed to efficiently plate and strip Mg, have not yet been proven to work with high voltage cathode materials that are needed to achieve high energy density. One possibility is that these electrolytes are inherently unstable on porous electrodes. To determine if this is indeed the case, the electrochemical properties of a variety of electrolytes were tested using a porous carbon coating on graphite foil and stainless steel electrodes. It was determined that the oxidative stability limit on these porous electrodes is considerably reduced as compared to those found using polished platinum electrodes. Furthermore, the voltage stability was found to be about 3 V vs. Mg metal for the best performing electrolytes. These results imply the need for further research to improve the stability of Mg electrolytes to enable high voltage Mg batteries.

Fervent Hype behind Magnesium Batteries: An Open Call to Synthetic Chemists—Electrolytes and Cathodes Needed

“…each oxygen atom represents aTHF solvent molecule). [56] On the other hand, magnesium organoborates with am agnesium dimer cation (Mg 2 (m-Cl) 3 ·6 THF) + have been reported to have similar oxidative stabilities on platinum as well as stainless steel and aluminum. Reproduced with the permission from Ref.…”

Cu9S5 Nanoflower Cathode for Mg Secondary Batteries: High Performance and Reaction Mechanism

“…The galvanostatic cycling was conducted within the voltage window of 0.1–2.2 V, and the results are given in Figure a–c. A lab‐made polytetrafluoroethylene (PTFE) cell is used to avoid corrosion caused by the electrolyte (Figure S1, Supporting Information) . As seen in Figure a, in the first discharge process, only a sloping curve was observed, while two flat discharge plateaus appeared at 1.5 and 1.0 V, respectively, during the second cycle.…”

“…2019, 7, 1800777 electrolyte ( Figure S1, Supporting Information). [25][26][27][28][29] As seen in Figure 2a, in the first discharge process, only a sloping curve was observed, while two flat discharge plateaus appeared at 1.5 and 1.0 V, respectively, during the second cycle. Then, the 1.5 V discharge plateau disappeared in the third cycle, and the 1.0 V plateau widened and the voltage increased to 1.1 V. At the same time, the corresponding charge plateau broadened, and the charge voltage decreased from 1.8 to 1.6 V. Figure 2a indicates that the polarization decreased and the capacity increased during the initial cycles.…”

“…As well demonstrated in Li and Na secondary batteries, the electrochemical conversion reaction gives an alternative method for transition-metal compounds to provide high capacities by utilizing their full oxidation states, since it is not constrained by the traditional intercalation chemistry. [18,19] It is believed that suitable cathode materials could be well widened if a conversion mechanism is introduced into Mg batteries. As Mg 2þ is a harder acid than Li þ , a softer base such as S 2À or Se 2À ions should be more advantageous to construct the cathode in light of the kinetics.…”

Magnesiumbatterien – ein Aufruf an Synthesechemiker: Elektrolyte und Kathoden dringend gesucht

“…[22] Dagegen gaben Nelson et al an, dass Magnesiumtetraphenylaluminat, das durch die Reaktion von 1 ¾quivalent Aluminiumtriphenoxid und 4 ¾quivalenten Phenylmagnesiumchlorid in situ erzeugt wurde,e ine hohe oxidative Stabilitäts owohl auf Edelstahl als auch auf Platin zeigt (Abbildung 9). [56] Magnesiumorganoborate mit einem Magnesium-Dimer-Kation (Mg 2 (m-Cl) 3 ·6 THF) + zeigten hingegen auf Platin sowie auf Edelstahl und Aluminium ähnliche oxidative Stabilitäten. [40] Lipson et al untersuchten die Stabilitätv ieler in situ erzeugter Elektrolyte,d ie freie Chloridionen enthalten und deshalb korrosiv sind, auf inerten Kohlenstoffelektroden sowie auf Edelstahl.…”