Rechargeable
magnesium (Mg) metal batteries are provided with potential
advantages over lithium counterparts with respect to volumetric capacity
and natural abundance (equivalent to low cost and sustainability).
However, Mg metal anodes suffer from surface passivating behavior
among numerous conventional Mg electrolytes, leading to irreversible
Mg plating/stripping behavior. Herein, a modified Mg metal anode with
a bismuth (Bi)-based artificial protective layer has been obtained
via a facile solution process (soaking briefly in bismuth trichloride
solution). This Bi-based protective layer is mainly composed of ion-conducting
Bi metal and corresponding alloy and electronically insulating magnesium
chloride. Various electrochemical tests and interface characterizations
have proved that the protected Mg electrodes effectively inhibit the
harmful parasitic reaction between Mg metal and noncorrosive Mg electrolyte,
which further enables suppression of uneven growth during repeated
Mg stripping/plating. More importantly, the assembled Mg–Cu2–x
S and Mg–O2 full
batteries utilizing the as-modified Mg anodes all deliver remarkably
improved performance owing to the superior protection properties of
a Bi-based artificial layer. These novel findings will inspire lot
of efforts to modify the Mg metal anode with targeted surface coatings
for high-performance rechargeable Mg batteries.
Chalcogenides have been viewed as important conversion-type Mg 2 + -storage cathodes to fulfill the high volumetric energy density promise of magnesium (Mg) batteries. However, the low initial Columbic efficiency and the rapid capacity degradation remain challenges for the chalcogenide cathodes, as the clear Mg 2 + -storage mechanism has yet to be clarified. Herein, we illustrate that the charge storage mechanism of the Cu 2À x Se cathode is a reversible displacement reaction along with a polyselenide (PSe) mediated solution process of anion-compensation. The unique anion redox improves charge storage, while the dissolution of PSe also leads to performance degradation. To address this issue, we introduce Mo 6 S 8 into the Cu 2À x Se cathode to immobilize PSe, which significantly improves performance, especially the reversible capacity (from 140 mAh g À 1 to 220 mAh g À 1 ). This work provides inspiration for the modification of the Mg 2 + -storage cathode, which is a milestone for high-performance Mg batteries.
Batteries, as highly concerned energy conversion system, have a great development prospect in various fields, especially in the field of energy powered vehicles. Multivalent ion batteries are getting more attention due to their low cost, high abundance in earth crust, high capacity and safety compared with Lithium batteries. Despite above advantages, several problems still need to be solved before multivalent ion batteries achieve large‐scale application, such as interfacial parasitic reaction, anode passivation, and dendrites. The replacement of liquid electrolytes with gel polymer electrolytes (GPEs) which pose high safety, high mechanical strength and simplified battery system, is an effective strategy to inhibit dendrite growth and improve electrochemical performance. This review mainly discusses the advantages and challenges of multivalent ion batteries including zinc, magnesium, calcium and aluminum batteries. Meanwhile, the major targets of this review are introducing the recent developments and making a summary of the future trends of GPEs in the multivalent ion batteries.
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