Graphene-Like-Armored Nanosheet Assemblies toward Fast and Stable High-Mass-Loading Sodium Storage

Sodium-ion batteries represent promising energy storage devices, yet their deployment is severely hampered by sluggish ion-transport kinetics and unstable electrode-electrolyte interfacial chemistry that deteriorate rate capability and cycling lifespan, particularly under high-loading electrode configurations. Here, we report a structural anode design comprising double-shelled TiO2 spheres assembled from cross-distributed 2 nm thick nanosheets and uniformly encapsulated by a graphene-like armor. This architecture enables predominantly surface-controlled sodium storage behavior with ultrafast reaction kinetics and exceptional stability, overcoming the long-standing trade-off between capacity, rate performance, and cycle life. The rationally designed electrode achieves a practically relevant areal capacity of 2.13 mAh cm-2 and outstanding rate capability (121 mAh g-1 at 100 C). Remarkably, it remains more than 90% of its capacity over 3,000 cycles at 5 C under a high mass loading of 10.5 mg cm-2, outperforming conventional anode structures. This work establishes a structural design strategy for advanced anodes applicable in practical high-power batteries.