Topologically Defective Lamellar Porous Carbon for Fast and High-Capacity Sodium-Ion Storage
A class of topologically defective lamellar porous carbon(TDLPC)is fabricated by a thermal-driven heteroatom removal strategy using crosslinked self-assembled lamellar block copolymers as precursors.The structures(lamellar morphologies,defects,closed pores,and open pores)of TDLPC are investigated using methods such as scanning electron microscopy(SEM),Raman spectroscopy,electron paramagnetic resonance(EPR)spectroscopy,transmission electron microscopy(TEM),small-angle X-ray scattering(SAXS)spectroscopy,and specific surface area and porosity analyzer.Results demonstrate that the removal of heteroatoms induces the rearrangement of adjacent carbon atoms,leading to formation of abundant topological defects as well as closed pores,while etching of in situ formed silica templates generates moderate open micro/mesopores.Specifically,defect sites with enhanced sodium adsorption can raise sloping capacity,closed pores with suitable sites for sodium filling can increase plateau capacity,and open pores with interconnected channels can facilitate ion transfer.Benefiting from the above structural advantages,when TDLPC is used as anodes for sodium-ion batteries,it can simultaneously exhibit high sloping capacity(130 mA·h/g)as well as high plateau capacity(83 mA·h/g),excellent rate performance(162 mA·h/g at 5 A/g),and long cycling stability(capacity retention of 94%after 500 cycles at 1 A/g).
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