A lead-free multiferroic ceramic of BiFe0.96Sc0.04O3–BaTiO3 is a type of ABO3 perovskite structure, belonging to the R3c space group, but exhibiting poor insulation and weak multiferroicity.

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Eco-friendly, multi-heteroatom-doped 3D hybrids were constructed for the first time by one-pot pyrolysis and showed excellent electrochemical performance.

In recent years, phosphate Na3V2(PO4)3 (NVP) has attracted considerable attention as a promising cathode for high-performance sodium ion batteries owing to its open 3D framework structure. However, low rate capacity of the material greatly hampers the practical application due to its poor conductivity. Herein, La-doped Na3V2–x La x (PO4)3/C materials were prepared by a combination process of sol–gel and carbon-thermal reduction methods. All materials possess NASICON-type structure with the R3̅C space group. No impurity can be detected, and a thin carbon layer is coated on the surface of the materials. The doping of La3+ significantly reduces internal resistance and enhances fast Na+ mobility. As a result, the material with the addition of 2% La3+ exhibits excellent cyclic performance and rate capability: a high initial reversible capacity of 105.4 mA h g–1 at 0.2 C, capacity retentions of 96.5% at 1 C after 200 cycles, and excellent rate performance of 92.6 mA h g–1 at 30 C. Under a high current density of 20 C for 3000 cycles, it can still deliver a superior reversible capacity of 73.5 mA h g–1 with a high capacity retention of 93.5%. Even at 50 C, the Na3V1.98La0.02(PO4)3/C electrode can release a satisfactory initial capacity of 79.9 mA h g–1 with an average Coulombic efficiency of 99.3% after 8000 cycles. Our work demonstrates that La3+-doped Na3V2(PO4)3/C may be a promising candidate of cathode for high-performance sodium ion batteries.

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In situ nitrogen‐doped hierarchical porous carbon was synthesized by using waste protein‐rich pig nails as precursors in a facile KOH activation method. The microstructure and electrochemical characteristics of the materials were investigated by tuning the amount of KOH. When the weight ratio of KOH to pig nails is 1 : 1, the obtained nitrogen‐doped hierarchical porous carbon (NHPC‐1) exhibits the largest specific surface area (2569 m2 g−1) with interconnected porous network structure, which are beneficial to ion/electron storage and transfer. In addition, abundant nitrogen of 2.8 at % in the NHPC‐1 also contributes to the high electrochemical activity of the supercapacitor during the charging/discharging process. As a result, the NHPC‐1 electrode in the supercapacitor exhibits a high specific capacitance of 231 F g−1 at 1 A g−1 and superior retention of 98 % after 5000 cycles at 1 A g−1 in 6 M KOH electrolyte. Additionally, the assembled symmetric device based on NHPC‐1 exhibits a high energy density of 7 Wh kg−1 at a power density of 500 W kg−1. Our study suggests that waste pig nails can act as low‐cost and renewable carbon precursors for high performance supercapacitor.

Figure 4. a)The CV curves of Zn@CuHCF//V 2 O 5 and bare Zn//V 2 O 5 full cells. b) The charging/discharging curves of Zn@CuHCF//V 2 O 5 cells. c) Rate performance. d) Cycling performance of full cells. e) Ragone plot of Zn@CuHCF//V 2 O 5 cell compared with previously reported AZIBs. [60][61][62][63][64][65][66] f) Schematic diagram of a flexible quasi-solid-state Zn@CuHCF//V 2 O 5 battery. g) The optical images of open circuit voltage of the flexible quasi-solid-state Zn@CuHCF//V 2 O 5 battery in various bending states. h) LED powered by two flexible quasi-solid-state Zn@CuHCF//V 2 O 5 batteries.

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