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Sodium ion batteries (SIBs) have been considered as a promising cost-effective alternative for grid energy storage for renewable energy sources such as wind- and solar power. In this work, a bismuth nano-spheres and porous carbon composite (Bi-NS@C) is developed via an oleate-oriented dual-phase interfacial reaction and a molten salt calcination process. Materials characterizations suggest that the Bi-NS with a size of 20–30 nm are uniformly distributed in the sponge-like porous carbon network. Such a structure could enable a conductive network, prevent particle aggregation, shorten the ions transportation pathways, accommodate volume change and prevent the collapse of the electrode. As a result, this anode delivers a reversible discharge capacity of 106 mAh g −1 after even 1000 cycles at 0.2 A g −1 . Even at 2 A g −1 , the specific capacity of the electrode can still retain at ∼110 mAh g −1 . The remarkable electrochemical performance of the Bi-NS@C composite suggests that the as-prepared nanocomposite can simultaneously enhance the Na + ion conductivity and electronic conductivity in the charge/discharge processes, which offer guidance in anode materials design and synthesis in SIBs. [ABSTRACT FROM AUTHOR]

• A universal approach for the preparation of hexagonal ring-like LDH was proposed. • A series of hexagonal ring-like LDH were synthesized by a universal NaOA-assisted TTS method. • The formation mechanism of nanoring was systematically studied. • As-prepared ring-like CoAlNi LDH exhibited enhanced supercapacitor performance than that of the plate-like LDHs. Hexagonal ring-like structure of ternary-component layered double hydroxide (LDH) could be promising materials for advanced energy storage and conversion systems. However, it is still a great challenge to present a universal and cost-effective approach to fabricate ternary-component LDH nanomaterials with ring-like micro-/nano-structure. In this work, a universal sodium oleate (NaOA)-assisted two-step two-phase solvothermal (TTS) method is developed to synthesize hexagonal ring-like structure of ternary-component LDH nanomaterials. This strategy is generic for synthesis of ring-like LDHs with different element components, such as CoAlNi, MgAlNi, and MgAlCo. The formation mechanism of nanorings constructed by TTS method is further systematically studied, which can be ascribed to the dissolution-recrystallization process driven by the solubility product of different reactant and Ostwald ripening effect. The ring-like CoAlNi LDH exhibited enhanced supercapacitor performance with a specific capacitance of 1339.6 F g−1 at 1 A g−1. Its asymmetric supercapacitor device exhibited high energy density (50.3 Wh kg−1 at a power density of 800 W kg−1) and stable cycling performance (about 82.2% capacitance retention over 3000 cycles). All of the electrochemical results of ring-like CoAlNi LDH are superior to that of pristine CoAlNi LDH nanosheets. The present work makes a significant contribution to the design and synthesis of ternary-component LDH with a unique hexagonal ring-like nano-architecture, as well as their potential applications in electrochemical energy storage. [ABSTRACT FROM AUTHOR]