Practical energy densities, cost, and technical challenges for magnesium‐sulfur batteries

Abstract

Amid burgeoning environmental concerns, electrochemical energy storage has rapidly gained momentum. Among the contenders in the "beyond lithium" energy storage arena, the magnesium-sulfur (Mg/S) battery has emerged as particularly promising, owing to its high theoretical energy density. However, the gap between fundamental research and practical application is still hindering the commercialization of Mg/S batteries. Here, through reviewing the recent developments of Mg/S batteries technologies, especially with respect to energy density and cost, we present the primary technical challenges on both materials and device level to surpass the energy density and cost-effectiveness of lithium-ion battery. While the high electrolyte-sulfur ratio and the expensive liquid electrolyte are significantly limiting the practical application of Mg/S batteries, we found that solid-state Mg electrolyte appears to be a feasible solution on the basis of energy density and cost evaluation.

Room‐temperature metal–sulfur batteries: What can we learn from lithium–sulfur?

“…[62][63][64][65][66] The soluble polysulfides can diffuse out of the sulfur cathode to the metal anode where they can react with the metal anodes, causing serious active material loss and fast capacity decay. 39,[67][68][69][70][71][72] In comparison with LiPS, partial sodium polysulfides (NaPS) and potassium polysulfides (KPS) are more soluble in the commonly used ether-based electrolytes, 73,74 and hence the polysulfide shuttle and the self-discharge behavior in Na-S and K-S batteries are more severe. [75][76][77] In cases of metal-S batteries with multivalent metal anodes (e.g., Mg, Ca, and Al), the polysulfide dissolution and shuttle are also involved, but are not significant as alkali-metal sulfur batteries.…”

“…Most issues associated with metal–S batteries are caused by the generation of soluble polysulfides and their ensuing shuttling between the cathode and the anode 62–66 . The soluble polysulfides can diffuse out of the sulfur cathode to the metal anode where they can react with the metal anodes, causing serious active material loss and fast capacity decay 39,67–72 . In comparison with LiPS, partial sodium polysulfides (NaPS) and potassium polysulfides (KPS) are more soluble in the commonly used ether‐based electrolytes, 73,74 and hence the polysulfide shuttle and the self‐discharge behavior in Na–S and K–S batteries are more severe 75–77 .…”

Rational Design Strategy of Novel Energy Storage Systems: Toward High‐Performance Rechargeable Magnesium Batteries

“…Although the working voltage of MgS battery is only above 1.0 V for the low reaction potential of S cathode (1.6 V versus Mg/Mg 2+ ), a high theoretical volumetric energy density (3221 Wh dm −3 ) for MgS batteries comparable to current LiS batteries (2800 Wh dm −3 ) could be realized due to the higher volumetric capacity of the Mg anode (3833 mAh cm −3 versus 2062 mAh cm −3 of Li anode). [105][106][107][108] However, MgS batteries are also facing a series of challenges before industrialization. First, similar to conventional RMBs, electrolytes which are compatible with Mg anode are required to achieve reversible Mg platting and stripping.…”

Exploration of the Unique Structural Chemistry of Sulfur Cathode for High‐Energy Rechargeable Beyond‐Li Batteries

“…[163][164][165] For example, there is limited availability of cathode materials compatible with Mg metal and electrolyte systems, sluggish reaction kinetics, and a high diffusion barrier for Mg 2þ ions. [166,167] Additionally, one of the major setbacks of the Mg/S battery is the formation of complex intermediate magnesium polysulfides, which impede the system with low reversibility and poor cyclic performance. [165,168] Despite the issues highlighted above, tremendous breakthroughs in rechargeable Mg/S batteries have been made in recent years.…”