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.