LAUSR

The potential for energy storage in carbonaceous materials has been demonstrated. Heteroatom doping, particularly nitrogen (N) doping can further enhance their electrochemical performance. The type of N configuration determines the reactivity of doped carbon. It remains a challenge, however, to achieve a high ratio of active N (N-5) in N doped carbon. Herein, a high proportion of active nitrogen-doped hard carbon (PTA-Lys-800) is synthesized by rational design of classical Mannich reaction using tannic acid (TA) and amino acid as precursors. For sodium ion batteries (SIBs), the PTA-Lys-800 provides outstanding cycling stability and rate performance (338.8 mAh g-1 at 100 mA g-1 for 100 cycles, a capacity retention of 86%; 131.1 mAh g-1 at 4 A g-1 after 5000 cycles). The excellent performance of PTA-Lys-800 is attributed to stable hierarchical pore structures, abundant defects, and high proportion of N-5 are formed during the carbonization process. Based on the results of detailed fundamental analysis, the pseudocapacitance mechanism contributes to the higher sodium storage process in PTA-Lys-800. The Na-adsorption mechanism is further explored through ex situ Raman technology. As a result of this work, a new scheme is presented for designing carbonaceous anode materials with high capacity and long cycle life.