Double‐Transition‐Metal MXene Films Promoting Deeply Rechargeable Magnesium Metal Batteries

Abstract

Magnesium metal batteries are promising candidates for next‐generation high‐energy‐density and low‐cost energy storage systems. Their application, however, is precluded by infinite relative volume changes and inevitable side reactions of Mg metal anodes. These issues become more pronounced at large areal capacities that are required for practical batteries. Herein, for the first time, double‐transition‐metal MXene films are developed to promote deeply rechargeable magnesium metal batteries using Mo2Ti2C3 as a representative example. The freestanding Mo2Ti2C3 films, which are prepared using a simple vacuum filtration method, possess good electronic conductivity, unique surface chemistry, and high mechanical modulus. These superior electro‐chemo‐mechanical merits of Mo2Ti2C3 films help to accelerate electrons/ions transfer, suppress electrolyte decomposition and dead Mg formation, as well as maintain electrode structural integrity during long‐term and large‐capacity operation. As a result, the as‐developed Mo2Ti2C3 films exhibit reversible Mg plating/stripping with high Coulombic efficiency of 99.3% at a record‐high capacity of 15 mAh cm−2. This work not only sheds innovative insights into current collector design for deeply cyclable Mg metal anodes, but also paves the way for the application of double‐transition‐metal MXene materials in other alkali and alkaline earth metal batteries.

MXene‐Based Current Collectors for Advanced Rechargeable Batteries

“…Furthermore, when MXene is used as a current collector, the restacking and layer spacing limitations may not accommodate large-sized electrode materials, making it difficult for large-scale energy storage equipment. Many organic molecules could be used to enlarge the [261] Copyright 2023, Wiley-VCH. f) Schematic of Mg deposition process on MXene film.…”

“…[265] For commercial Cu current collector, irregular Mg depositions may react with electrolyte and form "dead Mg," further resulting in irreversible Mg stripping/plating cycling. In 2023, Seh et al [261] reported that freestanding Mo 2 Ti 2 C 3 MXene film can serve as a current collector to reduce Mg nucleation energy barrier and improve reversibility (Figure 17a,b). In addition, MXene can accelerate Mg-ion transport and reduce charge transfer resistance.…”

“…[90] With the help of the 3D printing technique, 3D MXene array and lattice structure could be constructed to facilitate the nucleation of Li, further suppressing the growth of Li dendrites. In the past year, MXene-based current collectors have been successfully used in novel Al-ion, [91] Fe-metal, [92] and Mg-metal [93] battery systems with positive results.…”

Interface plasmon damping in the Cd33Se33/Ti2C MXene heterostructure

“…MXenes have predominantly been utilized in energy conversion and storage applications due to their promising electrochemical properties. [40][41][42][43][44][45][46][47][48][49][50] While metallic nanostructures made of gold, silver, aluminum, and copper have traditionally dominated plasmonic applications, plasmons are not limited to these metals alone. Plasmonic behavior has also been observed in other systems, including 2D materials with high electronic conductivity.…”

Chloride-Free Electrolyte Based on Tetrabutylammonium Triflate Additive for Extended Anodic Stability in Magnesium Batteries

“…Rechargeable magnesium batteries (RMBs) are a prime candidate for “post-Li-ion battery chemistry” due to their high volumetric capacity, low reduction potential, high abundance, and air stability. − However, RMBs suffer from passivation of the Mg anode with conventional electrolytes, which hinders Mg 2+ ion diffusion at the anode and leads to higher plating/stripping overpotential. − Anode passivation can be mitigated by either preconditioning the anode prior to cell fabrication or modifying the electrolyte with suitable additives. As the former is a complicated process, the latter solution is more viable, prompting research in electrolyte modification by additives to create a robust solid electrolyte interphase (SEI).…”