Synergistic engineering of defects and architecture in Co₃O₄@C nanosheets toward Li/Na ion batteries with enhanced pseudocapacitances

Constructing robust 2D−based energy storage nanomaterials by well−defined pore architectures and rational surface modification are critical yet daunting challenges for rechargeable alkali−ion batteries. Herein, a new−type 2D interwoven multi pores decorated Co₃O₄@N−doped carbon nanosheet with rich surface defects is proposed as lithium/sodium ion anodes for the first time. The combining experimental researches, microscopic structure characterization and dynamics analysis demonstrate that the multi porous structure provides large numbers of channels to accelerate Li⁺/Na⁺ transport, rational surface design creates abundant active sites for fast ions reactions, while robust carbon shell offers excellent ionic/electrical conductivity and structural integrity. The obtained bifunctional composites deliver superior rate performance and long−term cycle stability (~529 mA h g⁻¹ after 2000 cycles in LIBs and ~166 mA h g⁻¹ after 1700 cycles in SIBs) due to the synergistic contribution of the unique structure and surface defects. Furthermore, it still remains a high reversible capacity (>610 mA h g⁻¹ after 1000 cycles) in full cell. Kinetic analysis reveals the designed anode exhibits prominent pseudocapacitive behavior, enabling ultra−fast lithium/sodium storage and ultrahigh−rate capability. This work offers valuable insights for developing high performance energy storage devices.