Coral Polyp and Spine Dual‐Inspired Gradient Hierarchical Architecture for Ultrahigh‐Rate and Long‐Life Sodium Storage

Abstract Sodium‐ion batteries (SIBs) are promising alternatives to lithium‐ion batteries with similar working principles, cell structures, and material systems. However, attaining long‐term stability and high‐capacity performance of SIBs at ultrahigh rates remains a significant challenge due to the large ionic radius and slow kinetic behavior of Na + . Herein, a novel robust anode with a dual‐biomimetic gradient hierarchical architecture is proposed and provide a simple strategy to fabricate this sulfur‐doped mesoporous carbon concave hollow sphere/Ti 3 C 2 T x MXene (SCMX) anode. In addition, Cu 2 S nanoparticles are in situ embedded into the SCMX architecture by electrochemical induction during the cycling process to act as active sites, which enhances the rate performance and cycling stability. Relying on its hybrid architecture and in situ formed Cu 2 S, this SCMX anode can achieve high ion accessibility, rich active sites, rapid charge transfer, and favorable structure stability, as disclosed by in/ex situ characterizations. As a result, it exhibits high reversible capacity (745.6 mAh g −1 at 0.2 A g −1 ), ultrahigh‐rate capability (380.5 mAh g −1 at 50.0 A g −1 ), and long cycling stability (98.2% capacity retention after 10 000 cycles at 80.0 A g −1 ). This work is anticipated to accelerate the development of high‐performance SIBs and offer distinctive inspiration for the design of electrode structures/systems.