| Affiliation: | 1. Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR), 2 Fusionopolis Way, Innovis #08-03, Singapore, 138634 Singapore;2. School of Materials Science and Engineering, Beihang University, Beijing, 100191 P. R. China;3. School of Chemistry and Chemical Engineering, Guizhou University, Guiyang, Guizhou, 550025 P. R. China;4. School of Physical Science and Technology, ShanghaiTech University, Shanghai, 201210 P. R. China;5. Department of Mechanical and Energy Engineering and Integrated Nanosystems Development Institute, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, 46202 USA;6. Department of Mechanical and Energy Engineering and Integrated Nanosystems Development Institute, Purdue School of Engineering and Technology, Indiana University-Purdue University Indianapolis, Indianapolis, 46202 USA
School of Materials Engineering, Purdue University, West Lafayette, 47907 USA;7. College of Chemical and Biological Engineering, Zhejiang University, Hangzhou, 310027 P. R. China |
| Abstract: | Rechargeable magnesium batteries (RMBs) are promising next-generation low-cost and high-energy devices. Among all RMBs, anode-free magnesium metal batteries that use in situ magnesium-plated current collectors as negative electrodes can afford optimal energy densities. However, anode-free magnesium metal batteries have remained elusive so far, as their practical application is plagued by low Mg plating/stripping efficiency due to nonuniform Mg deposition on conventional anode current collectors. Herein, for the first time, an anode-free Mg-metal battery is developed by employing a 3D MXene (Ti3C2Tx) film with horizontal Mg electrodeposition. The magnesiophilic oxygen and reactive fluorine terminations in MXene enable an enriched local magnesium-ion concentration and a durable magnesium fluoride-rich solid electrolyte interphase on the Ti3C2Tx film surface. Meanwhile, Ti3C2Tx MXene exhibits a high lattice geometrical fit with Mg (≈96%) to guide the horizontal electrodeposition of Mg. Consequently, the developed Ti3C2Tx film achieves reversible Mg plating/stripping with high Coulombic efficiencies (>99.4%) at high-current-density (5.0 mA cm?2) and high-Mg-utilization (50%) conditions. When this Ti3C2Tx film is coupled with a pre-magnesized Mo6S8 cathode, the anode-free Mg-metal full-cell prototype exhibits a volumetric energy density five times higher than its standard Mg-metal counterpart. This work provides insights into the rational design of anode current collectors to guide horizontal Mg electrodeposition for anode-free Mg metal batteries. |
