Agar‐Derived Slope‐Dominated Carbon Anode with Puparium Like Nano‐Morphology for Cost‐Effective SIBs

Abstract The microstructure of hard carbons (HCs) including interlayer distance and lateral ab direction and pore size distribution plays a key role in regulating the sodium ions storage performance. Herein, by employing the gelatinous agar as a model precursor, series P‐doping HCs (P‐HC‐ x , x = 1, 2, 3, 4) are facilely prepared in batches via controllably regulating its crosslinking state by phytic acid (PA) at a low carbonization temperature of 750 °C, in which PA plays three roles (acid, flame retardant, and P‐doping precursor) in promoting the final structure of P‐HC‐x. Among those, the puparium like P‐HC‐2 with expanded carbon interlayer distance of 3.91 Å and shortened lateral ab direction of 9.4 nm delivers a high reversible capacity of 394 mAh g −1 at 0.1 A g −1 with high increased slope capacity of 363 mAh g −1 as well as an ultrafast charge‐discharge feature and a superlong cycle life. Pairing with the Na 3 V 2 (PO 4 ) 3 cathode, the fabricated sodium‐ion full cells exhibit the 132 mAh g −1 reversible capacity at 0.1 A g −1 , and 86% capacity retention after 100 cycles. This work successfully develops slope‐dominated high‐performance carbon anode, which will provide new insights for the microstructure regulation and design of other precursor‐derivedHCs.