Synthesis of Cu‐Doped Layered Transition Metal Oxide Cathode Materials Directly from Metal‐Organic Frameworks for Sodium‐Ion Batteries

Comprehensive Summary Mn‐based layered transition metal oxides are promising cathode materials for sodium‐ion batteries (SIBs) because of their high theoretical capacities, abundant raw materials, and environment‐friendly advantages. However, they often show insufficient performance due to intrinsic issues including poor structural stability and dissolution of Mn 3+ . Atomic doping is an effective way to address these structural degradation issues. Herein, we reported a new synthesis strategy of a Cu‐doped layered cathode by directly calcinating a pure metal‐organic framework. Benefiting from the unique structure of MOF with atomic‐level Cu doping, a homogeneous Cu‐doped layered compound P2‐Na 0.674 Cu 0.01 Mn 0.99 O 2 was obtained. The Cu substitution promotes the crystal structural stability and suppresses the dissolution of Mn, thus preventing the structure degradation of the layered cathode materials. A remarkably enhanced cyclability is realized for the Cu‐doped cathode compared with that without Cu doping, with 83.8% capacity retention after 300 cycles at 100 mA·g –1 . Our findings provide new insights into the design of atomic‐level doping layered cathode materials constructed by MOFs for high‐performance SIBs.