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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]

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/lithium titanate (Si/Li 2 TiO 3 ) nanocomposite is successfully prepared through the combination of a sol–gel approach with a high-temperature treatment as well as a high energy ball milling process. The structure and morphology of the composite are characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) analysis reveals Si particles are coated by the uniform disordered Li 2 TiO 3 layer with a thickness of about 5 nm. The investigation in cycling performances demonstrates that Si/Li 2 TiO 3 exhibits the improved cycling stability, with specific capacity of 471.0 mA h g −1 after 50 cycles and the capacity retention is 31.5%, much higher than pure Si. Compared with pure Si, Si/Li 2 TiO 3 shows better rate-capability, a reversible capacity of 315.2 mA h g −1 at 0.8 A g −1 is maintained. The higher ionic conductivity of Li 2 TiO 3 is responsible for the improved rate performance. In addition, the results derived from XRD, the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicate that lithium ions could react reversibly with Si, and electrochemically less active Li 2 TiO 3 turns into the Li–Ti–O ternary phase, which acts as a buffer matrix in the Si/Li 2 TiO 3 composite, thus improving the reversibility of electrode. [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]

The as-prepared binder-free Co 1−x S/MCF anode exhibits the desirable electrochemical performance for LIBs and SIBs, which can be attributed to the unique hierarchical nanostructure which provides enough active sites and internal space for volume expansion. [Display omitted] • The flexible Co 1−x S/MCF electrode is prepared via the electrospinning technique. • The Co 1−x S/MCF presents hierarchically hollow and multichannel structures. • The Co 1−x S/MCF electrode can effectively ease the huge volume expansion. • The Co 1−x S/MCF electrode shows high electrochemical performance for LIBs and SIBs. The exploration of prospective electrode materials represents great challenges for remarkable lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Herein, we report a reliable synthetic approach for the in-situ growth of the Co-based zeolitic imidazolate framework (ZIF-67) on electrospun nanofibers, followed by carbonization and sulfurization with the formation of free-standing Co 1−x S hollow polyhedrons anchored on multichannel carbon nanofibers (Co 1−x S/MCF) for LIBs and SIBs. The Co 1−x S/MCF electrode displays a high reversible capacity (813 mAh g−1 over 180 cycles at 0.1 A g−1), and stable cycle performance (559 mAh g−1 for 300 cycles at 1 A g−1) in LIBs. For SIBs, Co 1−x S/MCF electrode exhibits a favorable Na-storage capacity (433 mAh g−1 over 120 cycles at 0.1 A g−1). The as-prepared binder-free Co 1−x S/MCF anode demonstrates the advanced electrochemical properties for LIBs and SIBs. It is attributed to the particular multichannel nanostructure and the Co 1−x S hollow polyhedrons (Co 1−x S HPs), which provide enough active sites, and the internal void space effectively reduces the structural strain and eases the volume expansion to maintain structural integrity. This work gives insights to design a unique structure for promising LIBs and SIBs. [ABSTRACT FROM AUTHOR]

The as-prepared binder-free Co 1−x S/MCF anode exhibits the desirable electrochemical performance for LIBs and SIBs, which can be attributed to the unique hierarchical nanostructure which provides enough active sites and internal space for volume expansion. [Display omitted] • The flexible Co 1−x S/MCF electrode is prepared via the electrospinning technique. • The Co 1−x S/MCF presents hierarchically hollow and multichannel structures. • The Co 1−x S/MCF electrode can effectively ease the huge volume expansion. • The Co 1−x S/MCF electrode shows high electrochemical performance for LIBs and SIBs. The exploration of prospective electrode materials represents great challenges for remarkable lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Herein, we report a reliable synthetic approach for the in-situ growth of the Co-based zeolitic imidazolate framework (ZIF-67) on electrospun nanofibers, followed by carbonization and sulfurization with the formation of free-standing Co 1−x S hollow polyhedrons anchored on multichannel carbon nanofibers (Co 1−x S/MCF) for LIBs and SIBs. The Co 1−x S/MCF electrode displays a high reversible capacity (813 mAh g−1 over 180 cycles at 0.1 A g−1), and stable cycle performance (559 mAh g−1 for 300 cycles at 1 A g−1) in LIBs. For SIBs, Co 1−x S/MCF electrode exhibits a favorable Na-storage capacity (433 mAh g−1 over 120 cycles at 0.1 A g−1). The as-prepared binder-free Co 1−x S/MCF anode demonstrates the advanced electrochemical properties for LIBs and SIBs. It is attributed to the particular multichannel nanostructure and the Co 1−x S hollow polyhedrons (Co 1−x S HPs), which provide enough active sites, and the internal void space effectively reduces the structural strain and eases the volume expansion to maintain structural integrity. This work gives insights to design a unique structure for promising LIBs and SIBs. [ABSTRACT FROM AUTHOR]