Paper reinforced nitrogen-doped phenolic resin derived 2D self-interwoven hard carbon network anodes for high-energy sodium-ion storage

Although self-supporting hard carbon is extensively studied as an anode material for sodium-ion batteries, its practical application remains constrained by low initial coulombic efficiency (ICE) and low energy density. This study employs solution copolymerization to synthesize nitrogen-doped phenolic resin (NPR), and subsequently fabricates paper-reinforced NPR composites via resin-solution impregnation. Then, a 2D self-interwoven hard carbon (2DHC) is obtained by carbonizing the composite. The incorporation of paper leads to numerous closed pores after carbonization, thereby enhancing the plateau capacity of the 2DHC anode. The 2DHC anode exhibits a first-cycle discharge capacity of 366.57 mAh g −1 and an ICE of 85.81%. A sodium-ion full cell is assembled by pairing the 2DHC anode with a Na 2 NiFeMnO 6 cathode. After 120 cycles at 0.2 C, the full cell delivers a reversible capacity of 72 mAh g −1 and achieves an energy density of 279.54 Wh kg −1 . In this study, the intrinsic structural integrity of 2DHC enables its operation without metal current collectors or binders. These outstanding properties make it an ideal candidate material for developing next-generation eco-friendly energy storage devices.