Abstract
Development of practical rechargeable Mg batteries (RMBs) is impeded by their limited cycle life and rate performance of cathodes. As demonstrated herein, a copper‐porphyrin with meso‐functionalized ethynyl groups is capable of reversible two‐ and four‐electron storage at an extremely fast rate (tested up to 53 C). The reversible four‐electron redox process with cationic‐anionic contributions resulted in a specific discharge capacity of 155 mAh g−1 at the high current density of 1000 mA g−1. Even at 4000 mA g−1, it still delivered >70 mAh g−1 after 500 cycles, corresponding to an energy density of >92 Wh kg−1 at a high power of >5100 W kg−1. The ability to provide such high‐rate performance and long‐life opens the way to the development of practical cathodes for multivalent metal batteries.
Highlights
From portable electronics to electric vehicles and grid applications.[1]
Rechargeable Mg batteries (RMBs) utilizing a Mg anode are promising candidates for applications beyond Li-ion batteries owing to the Mg abundance and its bivalent nature.[5]
Tremendous advances in electrolyte development have been achieved in the past years, resulting in practical and noncorrosive magnesium electrochemistry.[6,7]
Summary
Ebrahim Abouzari-Lotf,*[a, b] Raheleh Azmi,[c] Zhenyou Li,[a, b] Shirin Shakouri,[b] Zhi Chen,[b]. Zhirong Zhao-Karger,[a, b] Svetlana Klyatskaya,[b] Julia Maibach,[c] Mario Ruben,*[b, d, e] and Maximilian Fichtner*[a, b]. G., sulfur) owing to the loss of active material upon dissolution of polysulfides into the electrolyte during the sulfur redox process.[15] In contrast to their inorganic counterparts, organic cathodes G., quinone-based materials) offer less rigid migration pathways for Mg2 + ions with lower migration barriers, which allow operation at higher rates Despite such advantages and the potential tuneability of redox properties in organic cathodes, the stable discharge capacity is usually quite below the theoretical values and the rate capability is limited.[16,17,18].
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