N- and O-codoped porous carbon nanosheets derived from a linear Schiff-base polymer for Li-ion batteries

Two-dimensional porous carbon nanosheets with large surface areas and high heteroatom contents are very appealing for applications in electrochemical energy storage. Herein, we offer a boulevard to prepare nitrogen- and oxygen-codoped carbon nanosheets (NOCNs) with high N, and O contents from a linear Schiff-base polymer (L-SBP), which was synthesized based on a convenient condensation reaction. Subsequently, NOCNs-T was achieved by pyrolysis of L-SBP at different temperatures (T). The derived NOCNs-800 offered a high specific surface area (SSA) of 478.7 m2 g−1 with a pore volume of 0.507 cm3 g−1. When employed as electrode materials for Li-ion batteries (LIBs), the Li-ion storage performance of NOCNs-T was notably improved after the pyrolysis of L-SBP under Ar atmosphere. Compared with NOCNs-700, and NOCNs-900, the as-prepared NOCNs-800 demonstrated a high reversible capacity with outstanding rate performance and cyclic durability. The discharge-specific capacity was maintained at about 380.4 mAh g−1 at 100 mA g−1 after 200 cycles. The excellent energy storage performance can be ascribed to the large SSA, high heteroatom contents, and suitable pores, offering abundant active sites and wettability.