A High‐Capacity Manganese‐Metal Battery with Dual‐Storage Mechanism

As a promising post lithium‐ion‐battery candidate, manganese metal battery (MMB) is receiving growing research interests because of its high volumetric capacity, low cost, high safety and high energy‐to‐price ratio. However, the low energy density, mainly constrained by scarce choices and unsatisfying capacity of cathodes, strictly bottlenecks the development of MMBs. In this work, a new class of cathodes based on novel dual‐storage mechanism (DSM) are reported. Working principles of DSM are revealed and deeply understood via ex‐situ X‐ray diffraction and X‐ray photoelectron spectroscopy. Besides, a proof‐of‐concept DSM‐based Cu1.8S cathode, which shows the highest specific capacity of 220 mAh g‐1 and 97.1% higher energy density than previously reported cathodes in storing Mn2+ ions, is presented. The key determinants on DSM and design strategies for next‐generation cathodes are revealed via theoretical calculations. This work provides a new class of high‐capacity cathode materials for MMBs, which is expected to draw inspirations to further enhance the energy density of MMBs.