Freestanding nitrogen-doped porous carbon nanofiber (NCNF) mats were prepared by electrospinning polyacrylonitrile/poly­(m-aminophenol) (PAN/PmAP) precursor blends with different polymeric compositions followed by thermal stabilization and carbonization. The morphology, pore structure, and surface elemental compositions of as-prepared NCNFs were characterized by different techniques such as scanning electron microscopy, transmission electron microscopy, N2 adsorption, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The charge-storage capability of the fabricated NCNFs was investigated in KOH electrolyte. The electrochemical performances of NCNFs were evaluated by varying the PmAP loading in the blend compositions. The highest specific capacitance of 347.5 F g–1 at 0.5 mA cm–2 together with a capacitance retention of 173.2 F g–1 at 20 mA cm–2 was achieved for the PAN:PmAP (85:15 w/w) NCNFs (NCNF85:15). The volumetric capacitance of 200.8 F cm–3 at 0.5 mA cm–2 was recorded for NCNF85:15. The NCNF85:15 showed the maximum energy density of 12.1 Wh kg–1 at 0.093 kW kg–1 and good cycling stability with 90.5% capacitance retention after 10 000 cycles. The excellent capacitive performances of the NCNF85:15 were attributed to high effective surface area, high content of mesoporosity, good conducvity, and high fraction of heteroatom-doped carbon, which result in both electrochemical double-layer and Faradaic capacitance contributions.

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Carbon-coated Si/carbon nanotube/graphene oxide (C-Si/CNT/GO) microspheres with a robust core–shell composite structure were successfully fabricated by efficient and scalable spray-drying and chemical vapor deposition (CVD) for application as a lithium-ion battery (LIB) anode. The amphiphilic GO nanoparticles facilitated the uniform dispersion of Si nanoparticles by suppressing the CNT aggregation in the Si/CNT/GO microspheres, efficiently forming a robust Si/CNT/GO microsphere composite structure. The surface of the Si/CNT/GO microsphere composite was coated with carbon using CH4 via CVD to enhance its cycling performance. The four building block components, namely, Si nanoparticles, CNTs, and GO nanoparticles as the core and the carbon-coating layers as the shell, provided high electrochemical capacity, excellent electrical conductivity, efficient buffer space for the volume expansion of the Si nanoparticles, and high structural stability during lithiation/delithiation. The C-Si/CNT/GO composite anode also exhibited excellent electrochemical performance with high specific capacity (2921 mAh g–1 at 100 mA g–1), long cycle life (1542 mAh g–1 at 200 mA g–1 after 100 cycles), and high charge/discharge rate (1506 mAh g–1 at 6 A g–1). This approach for fabricating core–shell structured Si-based composite anodes with excellent electrochemical performance will provide a significant breakthrough for developing next-generation LIBs.