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We reported a controlled synthesis method to obtained carbon spheres with tunable geometry under low ZnCl 2 aqueous solution conditions using polytriazine as a precursor. The polytriazine precursor was polymerized by mixing/reaction of 2,6-diaminopyridine and formaldehyde in the presence of a diluted ZnCl 2 aqueous system. The obtained nanospheres were then decomposed to adulterate nitrogen porous carbon nanospheres (N-PCNSs) by the decomposition and blistering process at high temperature by degrees. ZnCl 2 worked as a solid-template and played the role of a stabilizing and foaming agent in the reaction. The as-prepared N-PCNSs with controllable spherical geometry, large micro-/mesoporous volume and high nitrogen content (∼8.5 wt %) were employed in electric double-layer capacitors that have a good specific capacitance (636 F/g at 1 A/g) and are long lasting. Besides, the N-PCNS delivered a high energy density of 22.1 Wh/Kg at a power density of 500 W/kg.

In response to the increasing concern for energy management, molybdenum disulfide (MoS 2 ) has been extensively researched as an attractive anode material for sodium-ion batteries (SIBs). The proficient cycling durability and good rate performance of SIBs are the two key parameters that determine their potential for practical use. In this study, nature-inspired three-dimensional (3D) MoS 2 ultrathin marigold flower-like microstructures were prepared by a controlled hydrothermal method. These microscale flowers are constructed by arbitrarily arranged but closely interconnected two-dimensional ultrathin MoS 2 nanosheets. The as-prepared MoS 2 microflowers (MFs) have then been chemically wrapped by layered graphene sheets to form the bonded 3D hybrid MoS 2 -G networks. TEM, SEM, XRD, XPS, and Raman characterizations were used to study the morphology, crystallization, chemical compositions, and wrapping contact between MoS 2 and graphene. The ultrathin nature of MoS 2 in 3D MFs and graphene wrapping provide strong electrical conductive channels and conductive networks in an electrode. Benefitting from the 2 nm ultrathin crystalline MoS 2 sheets, chemically bonded graphene, defect-induced sodium storage active sites, and 3D interstitial spaces, the prepared electrode exhibited an outstanding specific capacity (606 mA h g -1 at 200 mA g -1 ), remarkable rate performance (345 mA h g -1 at 1600 mA g -1 ), and long cycle life (over 100 cycles with tremendous Coulombic efficiencies beyond 100%). The proposed synthesis strategy and 3D design developed in the present study reveal a unique way to fabricate promising anode materials for SIBs.

Low cycling stability and poor rate performance are two of the distinctive drawbacks of most electrode materials for sodium-ion batteries (SIBs). Here, inspired by natural flower structures, we take advantage of the three-dimensional (3D) hierarchical flower-like stable microstructures formed by two-dimensional (2D) nanosheets to solve these problems. By precise control of the hydrothermal synthesis conditions, a novel three-dimensional (3D) flower-like architecture consisting of 2D Na 2 Ti 3 O 7 nanosheets (Na-TNSs) has been successfully synthesized. The arbitrarily arranged but closely interlinked thin nanosheets in carnation-shaped 3D Na 2 Ti 3 O 7 microflowers (Na-TMFs) originate a good network of electrically conductive paths in an electrode. Thus, Na-TMFs can get electrons from all directions and be fully utilized for sodium-ion insertion and extraction reactions, which can improve sodium storage properties with enhanced rate capability and super cycling performance. Furthermore, the large specific surface area provides a high capacity, which can be ascribed to the pseudo-capacitance effect. The wettability of the electrolyte was also improved by the porous and crumpled structure. The remarkably improved cycling performance and rate capability of Na-TMFs make a captivating case for its development as an advanced anode material for SIBs.