Synthesis of Nitrogen‐Doped Mesoporous Structures from Metal–Organic Frameworks and Their Utilization Enabling High Performances in Hybrid Sodium‐Ion Energy Storages

Abstract

Abstract Sodium‐ion energy storage is of the most attractive candidate for commercialization adoption due to the safety and cost demands of large‐scale energy storage systems, but its low energy density, slow charging capability, and poor cycle stability are yet to be overcome. Here, a strategy is reported to realize high‐performance sodium‐ion energy storage using battery‐type anode and capacitor‐type cathode materials. First, nitrogen‐doped mesoporous titanium dioxide (NMTiO2) structures are synthesized via the controlled pyrolysis of metal–organic frameworks. They exhibit interconnected open mesopores allowing fast ion transport and robust cycle stability with nearly 100% coulombic efficiency, along with rich redox‐reactive sites allowing high capacity even at a high rate of ≈90 C. Moreover, assembling the NMTiO2 anode with the nitrogen‐doped graphene (NG) cathode in an asymmetric full cell shows a high energy density exceeding its counterpart symmetric cell by more than threefold as well as robust cycle stability over 10 000 cycles. Additionally, it gives a high‐power density close to 26 000 W kg−1 outperforming that of a conventional sodium‐ion battery by several hundred fold, so that full cells can be charged within a few tens of seconds by the flexible photovoltaic charging and universal serial bus charging modules.

Keywords

• high energy density
• hybrid sodium‐ion energy storage
• N‐doped mesoporous structures
• robust cycle stability
• ultrafast charging