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Abstract Searching for advanced anode materials with exceptional electrochemical performance is essential for next-generation rechargeable batteries. The selection and structural design of anode materials are pivotal in the development of high-performance batteries. Herein, we demonstrate the preparation of uniform NiCo 2 O 4 nanotubes via a simple and cost-effective electrospinning technique followed by calcination in the air. Impressively, the advantages and importance of NiCo 2 O 4 nanotubes as an anode in lithium-ion batteries (LIBs) is demonstrated, which surpass their respective monometallic oxides in terms of electrochemical performance. Encouragingly, the as-obtained NiCo 2 O 4 nanotubes as an anode for sodium-ion batteries (SIBs) exhibit appealing electrochemical performance, such as high initial discharge capacity (879 mAh g−1 at 100 mA g−1), good rate capability, and excellent cycling stability. Moreover, a reversible capacity of 420 mAh g−1 at a current density of 100 mA g−1 can be maintained even after 100 cycles, corresponding to around 72% of the second cycle discharge capacity (584 mAh g−1). It is worth noting that this facile technique may provide a feasible way for the preparation of other functional materials with tube-like architectures for application in energy-storage device. Graphical abstract An advanced NiCo 2 O 4 nanotubes anode has been successfully prepared through a simple and cost-effective electrospinning technique followed by calcination in air. The as-obtained NiCo 2 O 4 nanotubes exhibits appealing electrochemical performance, such as high initial discharge capacity, good rate capability, and excellent cycling stability. Image 1 Highlights • NiCo 2 O 4 nanotubes are prepared through an electrospinning technique. • The NiCo 2 O 4 nanotubes surpass their respective monometallic oxides in terms of electrochemical performance in LIBs. • The NiCo 2 O 4 nanotubes as anode for SIBs present excellent electrochemical properties. • The electrospinning technique can be extended to prepare other functional materials in energy-storage devices. [ABSTRACT FROM AUTHOR]

Core-shelled NiFe 2 O 4 /NiO@Fe 2 O 3 nanocubes were synthesized based on Prussian blue analogues. The core-shelled structure was built through ion-exchange process in aqueous solution, and was remained after calcination. Different concentrations of ferrous affect the size and surface states of PBA precursors and its successor. Fabricated core-shelled NiFe 2 O 4 /NiO@Fe 2 O 3 nanocubes produced with the PBA precursor that soaked in the solution of ferrous ion with the highest concentration in this work appears the most stable capacity during cycles, because of its more homogeneous Fe 2 O 3 layer surface and more complete crystal. At the current density of 100 mA/g, it offers an initial capacity of 1587.96 mA h/g, and the second capacity of 967.91 mA h/g, that was remained as 806.1 mA h/g after 50 cyles. At 500 mA/g, it performs a capacity of 472.5 mA h/g after 500 cycles with a strong stability. • Core-shelled structure is built through ion exchange process. • Ion concentrations in ion exchange process sever different surfaces. • Complete Fe 2 O 3 shell layer permits more stability during cycling. • Suitable calcined temperature is detected for high performance material. [ABSTRACT FROM AUTHOR]

A facile two-step method is developed to synthesize three dimensional (3D) hierarchical CaCo 2 O 4 architectures as high-performance electrode materials for lithium ion batteries (LIBs) and oxygen evolution reaction (OER). Our strategy involves a simple poly(vinylpyrolidone) (PVP)-assisted hydrothermal route and subsequent thermal treatment to produce flowerlike CaCo 2 O 4 nanostructures with a size of ∼500 nm, which is constructed by some neighboring vertical nanoplates. Whereas, the absence of PVP results in the formation of CaCo 2 O 4 microspheres, further indicating the vital role of PVP in favor of the oriented crystal growth of Co-based oxides. Benefited from the unique structural features, the resultant CaCo 2 O 4 nanoflower presents excellent cycling stability (∼560 mAh g−1 after 100 cycles at 50 mA g−1) and remarkable rate capability. Apart from superior lithium storage properties, more strikingly, CaCo 2 O 4 nanoflower demonstrates a promising candidate as a noble metal-free electrocatalyst for oxygen evolution reaction, which will spur us to find more novel functional nanomaterials for wide applications. • 3D hierarchical CaCo 2 O 4 architectures have been synthesized. • CaCo 2 O 4 nanoflower presents high lithium-storage performance. • CaCo 2 O 4 nanoflower presents high oxygen evolution reaction performance. [ABSTRACT FROM AUTHOR]

• Silicon is obtained from photovoltaic industrial waste through simple purification. • N-doped carbon ensures fast charge transfer and structural stabilization. • Si/NC electrode has a high specific capacity both in half-cell and full-cell. Silicon (Si) is considered to be one of the most promising anode materials for the next generation of lithium-ion batteries (LIBs). However, the practical application of Si anode is still high cost and hindered by huge volume change. It is significant to produce high-performance Si anode of LIBs inexpensively. Herein, we report the Si/N-doped carbon (Si/NC) composite anode materials constructed by recycling Si waste from the photovoltaic industry as raw materials after simple purification and polydopamine (PDA)-derived carbon coating. The Si micro/nano-plates coated with the NC can facilitate electron transfer and inhibit the volume expansion of Si to stabilize the structure of composites. The resulting Si/NC electrode exhibits a high discharge capacity of 1139 mAh g−1 at 1 A g−1 over 200 cycles. Moreover, the full-cell (LiFePO 4 //Si/NC) presents excellent cycling performance (108 mAh g−1 at 0.5 A g−1 over 200 cycles). This work not only offers a reasonable solution for the acquirement of Si anode from the photovoltaic industry but also provides a new strategy for the preparation of anodes for the next generation of LIBs, which may bring great economic benefits. [ABSTRACT FROM AUTHOR]