3D N-doped graphene–CNT networks (NGCs) can be obtained by hydrothermal treatment, freeze-drying and subsequent carbonization of graphene oxide-dispersed pristine CNTs in the presence of pyrrole. The resulting NCGs used as a supercapacitor show high specific capacitance, good rate capability and still retain ∼96% of the initial capacitance even after 3000 cycles.

MnO@C core–shell nanoplates with a size of ∼150 nm have been prepared via thermal treatment deposition of acetylene with the precursor of Mn(OH)₂ nanoplates, which has been hydrothermally synthesized. The thickness of the carbon shells varied from ∼3.1 to 13.7 nm by controlling the treatment temperature and reaction duration time. The electrochemical performance of the MnO@C nanoplates, which were synthesized at 550 °C for 10 h with a carbon shell thickness of ∼8.1 nm, display a high reversible capacity of ∼770 mA h g⁻¹ at a current density of 200 mA g⁻¹ and good cyclability after prolonged testing, which is higher than that of MnO@C nanoplates with a carbon shell thickness of ∼3.1, 4.0, 4.2, 10.9 and 13.7 nm.

Fe₃O₄@C core–shell nanorings (R-Fe₃O₄@C) were fabricated by a synchronous reduction and carbon deposition process. As the anodes for lithium-ion batteries, these R-Fe₃O₄@C exhibit a high capacity, excellent cycling stability and good rate performance. This ring-shaped core–shell nanostructure design may pave the way to enhance electrochemical performances of electrode materials.

Rod-like Sb–C composite has been synthesized by a synchronous reduction and carbon deposition process. The Sb–C composite anode exhibits a reversible capacity of 478.8 mA h g⁻¹ at 100 mA g⁻¹ after 100 cycles for Li-ion batteries and exhibits a reversible capacity of 430.9 mA h g⁻¹ at 50 mA g⁻¹ after 100 cycles for Na-ion batteries.

A series of phosphorus-doped hard carbon (PHC-Ts) was fabricated by directly annealing a phosphoric acid solidified epoxy resin over a wide temperature range to study the evolution of P-containing groups and the microstructure with increasing temperature, and to evaluate the Na-storage performance. A correlation between them has been well established. As the carbonization temperature increases, the P-containing groups undergo a transition from P–O and P–C bonds to higher active P–P bonds with a non-monotonic decrease in the interlayer distance. The high number of active P-containing groups and large interlayer distances provide more active sites and fast ion transmission channels, which jointly contribute to the excellent electrochemical performance. The obtained PHC-700 electrodes have the largest interlayer distance and highest total activity with many P–C bonds, showing a high capacity of 379.3 mA h g⁻¹ at 0.1 A g⁻¹, a superb rate capability of 158.1 mA h g⁻¹ at 5.0 A g⁻¹, and a long-term cycling stability without the loss of capacity after 6500 cycles at 5.0 A g⁻¹.

Fe₃O₄ nanoflakes in an N-doped carbon matrix (Fe₃O₄ NF@NC) were prepared by solvothermal synthesis of Fe₃O₄ nanoflakes and in situ polymerization of pyrrole on the surface of Fe₃O₄ followed by heat treatment. The Fe₃O₄ NF@NC is composed of Fe₃O₄ nanoflakes with a width of 50–60 nm and a thickness of 10 nm dispersed in the N-doped carbon matrix. The carbon content varies from 18% to 50% on controlling the amount of pyrrole added, therefore the Fe₃O₄ NF@NC with 44% carbon content performs the best. Due to the cooperation of the two-dimensional (2D) structure of Fe₃O₄ nanoflakes and the N-doped carbon matrix, the obtained Fe₃O₄ NF@NC (44% carbon content) exhibits electrochemical performance with a reversible capacity of 1046 mA h g⁻¹ at 0.2 C (1 C = 924 mA g⁻¹) over 200 cycles, 662 mA h g⁻¹ at 1 C after 500 cycles and 600 mA h g⁻¹ at 5 C over 200 cycles.