Edge‐Nitrogen‐Rich Carbon Dots Pillared Graphene Blocks with Ultrahigh Volumetric/Gravimetric Capacities and Ultralong Life for Sodium‐Ion Storage

The development of stable electrode materials for sodium‐ion batteries (NIBs) with excellent rate capacity, high volumetric/gravimetric capacity, and ultralong‐term cycling stability still remains a challenge. Herein, a novel strategy for the synthesis of edge‐nitrogen‐rich carbon dots pillared graphene blocks (N‐CDGB) through self‐polymerization of aniline into graphene oxide blocks, and subsequent carbonization is developed. Due to high bulk density (1.5 g cm−3) and integrated lamellar structure with large edge‐interlayer spacing (4.2 Å) pillared by nitrogen‐doped carbon dots (95% edge‐nitrogen content), the dense N‐CDGB shows robust structural stability, fast ion/electron transfer pathways, and more active sites for sodium storage. As a result, the N‐CDGB electrode exhibits ultrahigh reversible volumetric and gravimetric capacities (780 mAh cm−3/520 mAh g−1 at 0.02 A g−1) far exceeding those of graphene (108 mAh cm−3/290 mAh g−1) and hard carbon (297 mAh cm−3/311 mAh g−1), excellent rate capability (118 mAh g−1/177 mAh cm−3 at 10 A g−1), and superior cycling stability up to 10 000 cycles with almost no capacity loss at 10 A g−1. This work signifies the superiority of densely pillared structure in the future development of NIBs with high volumetric/gravimetric capacity and ultralong‐term cycling stability. Edge‐nitrogen‐rich carbon dots pillared graphene blocks synthesized from natural graphite exhibit ultrahigh volumetric/gravimetric capacities (780 mAh cm−3/520 mAh g−1 at 0.02 A g−1), excellent rate performance, and ultralong cycle life.