Recent Advances in Rechargeable Magnesium‐Based Batteries for High‐Efficiency Energy Storage

Abstract

of lithium resources in the earth's crust (0.0022 wt%). [9] Therefore, it is critical to develop new battery systems. [10] Multivalent-ion batteries can in principle provide higher energy density than monovalent LIBs, which could overcome the aforementioned problems by employing a non-Li metallic anode. [11][12][13] Among various candidates, rechargeable magnesium batteries have many advantages over LIBs, such as abundant Mg resources, small ionic radius (0.72 Å) and high theoretical volumetric capacity (3833 mAh cm −3 ) (Figure 1a). Particularly, RMBs are inherently safer than LIBs because metallic Mg anodes are dendrite-free upon cycling. [14][15][16][17] In addition, Mg also possesses higher oxidative stability than lithium. [18] The configurations and working mechanisms of RMBs are similar to those of LIBs (Figure 1b,c). However, the current research on RMBs still faces many challenges. Particularly, metallic Mg anodes have a strong tendency to form an insulated and passivating surface layer, which kinetically blocks electrochemical reactions at room temperature. [19][20][21] Such passivating layers engender difficulty for choosing compatible electrodes and electrolytes. [22,23] In addition, many RMBs electrolytes are air-sensitive, highly corrosive and flammable, [24,25] which poses a threat to their practical applications. Additionally, it is challenging to quest for suitable cathode materials with the rapid intercalation/ deintercalation of Mg 2+ at room temperature, considering the complex reaction mechanism of Mg-based electrochemistry. Many useful pioneering works have been devoted to developing cathode materials for RMBs (Figure 1d). [26][27][28] The strong electrostatic interaction of Mg 2+ inevitably results in sluggish kinetics, which is kinetically slower than Li + , especially at room temperature. [19] In this review, we summarize recently developed cathode materials for rechargeable magnesium-ion batteries. The anode materials beyond Mg metal are also discussed. Furthermore, we explored other Mg-based energy storage technologies, including Mg-air batteries, Mg-sulfur batteries, and Mg-iodine batteries. This review could also provide basic knowledge and valuable strategies for the advancement of high-energy-density rechargeable magnesium-based batteries. Cathode MaterialsSimilar to LIBs, the working mechanism of RMBs batteries are based on the shuttle of Mg 2+ ions between cathode and anode Benefiting from higher volumetric capacity, environmental friendliness and metallic dendrite-free magnesium (Mg) anodes, rechargeable magnesium batteries (RMBs) are of great importance to the development of energy storage technology beyond lithium-ion batteries (LIBs). However, their practical applications are still limited by the absence of suitable electrode materials, the sluggish kinetics of Mg 2+ insertion/extraction and incompatibilities between electrodes and electrolytes. Herein, a systematic and insightful review of recent advances in RMBs, including intercalation-based cathode materials and conversion...

Recent Progress and Challenges in the Optimization of Electrode Materials for Rechargeable Magnesium Batteries

“…Benefited from this unique structure, about two Mg 2+ ions can be intercalated into each formula unit. [103] Moreover, the micro-sized Mo 6 S 8 also can deliver outstanding Mg ions storage performance when used as practical cathode material for RMBs. [40,104] Figure 2b shows the voltage profile with the intercalation of Mg 2+ into Mo 6 S 8 .…”

Hydrated MgxV5O12 Cathode with Improved Mg2+ Storage Performance

“…Despite the straightforward concept of taking advantage of a divalent cation, developing rechargeable and stable MIBs has been plagued by various materials limitations, especially the lack of suitable intercalation electrode materials and stable electrolytes featuring wide electrochemical windows. [ 12–15 ] Indeed, the greatest of these limitations on simulating the working mechanism of LIBs using intercalation cathodes and anodes is primarily caused by the sluggish solid‐state diffusion of divalent Mg ion. This is strongly related to the large polarization of anionic frameworks of electrodes and more intense repulsions among the intercalated divalent Mg ions due to a higher charge‐to‐radius ratio of Mg 2+ compared to Li + .…”

Advanced High‐Performance Potassium–Chalcogen (S, Se, Te) Batteries

“…[ 1 ] In order to meet the demand for energy storage market, exploitation of alternative energy storage systems with long‐term sustainability, cost‐effectiveness, and high energy density is quite urgent and important, such as sodium ion batteries, [ 2 ] sodium–sulfur batteries, [ 3 ] potassium ion batteries (PIBs), [ 4 ] zinc ion batteries, [ 5 ] aluminum ion batteries, [ 6 ] and magnesium ion batteries. [ 7 ] In very recent years, potassium, which lies in the same group with lithium, begins to come into scientists’ view due to their unique advantages. [ 8 ] Relatively high abundance of potassium element (1.5 wt%) can lead to its lower‐cost refinement than that of lithium while its widespread distribution both on the earth's crust and in the oceans also contributes to broader accessible pathways.…”