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The sodium storage performance of Ge-based materials suffers from poor cycling stability caused by the volume variation and collapse of the structure during cycling process. In this work, Cu3Ge coated by nitrogen-doped carbon (Cu3Ge-NC) nanorods are prepared by annealing the mixture of CuGeO3 nanowires and polyacrylonitrile which acts as nitrogen and carbon source. As anode materials for sodium ion batteries, the outside carbon shell inhibits the serious volume change caused by Na+ insertion/extraction, and the Cu3Ge alloy enhances the sodiation capacity with rapid electron transfer and fast reaction kinetics. Corresponding kinetic analysis indicates pseudocapacitive behaviors play a dominant role in the total capacity at high rates. Hence, the Cu3Ge-NC exhibits favorable rate capability and cycling stability, which delivers a reversible capacity of 160 mAh g−1 for 500 cycles at a current density of 100 mA g−1.

Ternary copper tin sulfides (CTS) have been attracted great attention as anode materials for lithium ion batteries (LIBs) owning to their high theoretical capacities and unique lithium storage mechanisms. However, the practical applications of CTS are plagued from the serious volumetric variation during the charge/discharge process. Herein, a high Cu/(Sn + S) element ratio copper tin sulfides, Cu4SnS4/Sn (CTS-4), with unique walnut-like microspheres was successfully prepared and firstly investigated as LIB anode materials. Compared with low Cu/(Sn + S) ratio Cu2SnS3 (CTS-3), CTS-4 delivers efficient lithium storage performance, cycling stability and rate capability. The considerable electrochemical performance is attributed to the higher conductivity and favorable Li+ diffusion coefficient of CTS-4 resulting from unique element ratio. This work will provide insight towards designing and building new anode materials for high-performance LIBs.

A novel silicon nanowire film anode was successfully prepared by a combination of magnetron sputtering deposition and metal-catalyzed electroless etching technology. Scanning electron microscopy revealed the formation of a Si film composed of nanowires with a diameter of ~70 nm and lengths of ~3.5 μm. As-prepared Si nanowire film is directly grown on current collectors without binders and carbon additives, which provides a good contact and adhesion of them to current collector. Furthermore, the defined spacing of nanoscale Si nanowire allows Si to undergo large volume change during the alloying/dealloying process without loss of its integrity. These structural features of the resulting Si nanowire make it a promising anode for lithium-ion batteries with remarkably improved electrochemical performance compared with the Si film-based electrode prepared without metal-catalyzed electroless etching process.

Copper tin sulfides (CTSs) have widely been investigated as electrode materials for supercapacitors owing to their high theoretical pseudocapacitances. However, the poor intrinsic conductivity and volume change during redox reactions hindered their electrochemical performances and broad applications. In this study, carbon quantum dots (CQDs) were employed to modify CTSs. The structures and morphologies of obtained materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD revealed CTSs were composed of Cu2SnS3 and Cu4SnS4, and TEM suggested the decoration of CQDs on the surface of CTSs. With the decoration of CQDs, CTSs@CQDs showed a remarkable specific capacitance of 856 F·g−1 at 2 mV·s−1 and a high rate capability of 474 F·g−1 at 50 mV·s−1, which were superior to those of CTSs (851 F·g−1 at 2 mV·s−1 and 192 F·g−1 at 50 mV·s−1, respectively). This was mainly ascribed to incorporation of carbon quantum dots, which improved the electrical conductivity and alleviated volume change of CTSs during charge/discharge processes.

Atomically modified graphitic carbon nitride quantum dots (QDs), characterized by strongly increased reactivity and stability, are developed. These are deposited on arrays of TiO2 nanopillars used as a photoanode for the photoelectrochemical water splitting. This photoanode shows excellent stability, with 111 h of continuous work without any performance loss, which outperforms the best‐reported results by a factor of 10. Remarkably, our photoanode produces hydrogen even at zero bias. The excellent performance is attributed to the enhancement of photoabsorption, as well as to the promotion of charge separation between TiO2 nanopillars and the QDs.

Germanium is considered as a potential anode material for sodium-ion batteries due to its fascinating theoretical specific capacity. However, its poor cyclability resulted from the sluggish kinetics and large volume change during repeated charge/discharge poses major threats for its further development. One solution is using its ternary compound as an alternative to improve the cycling stability. Here, high-purity CuGeO3 nanowires were prepared via a facile hydrothermal method, and their sodium storage performances were firstly explored. The as-obtained CuGeO3 delivered an initial charge capacity of 306.7 mAh g−1 along with favorable cycling performance, displaying great promise as a potential anode material for sodium ion batteries.

In this study, ternary Cu2SnS3 (CTS) nanostructure materials with high crystallinity were successfully prepared via a facile solvothermal method, which was followed by high-temperature treatment. The morphology of the as-synthesized samples is uniform flower-like spheres, with these spheres consisting of hierarchical nanosheets and possessing network features. Sodium storage measurements demonstrate that the annealed CTS electrodes have high initial reversible capacity (447.7 mAh&middot, g&minus, 1 at a current density of 100 mA&middot, 1), good capacity retention (200.6 mAh&middot, 1 after 50 cycles at a current density of 100 mA&middot, 1) and considerable rate capability because of their high crystallinity and unique morphology. Such good performances indicate that the high crystallinity CTS is a promising anode material for sodium ion batteries.

In this work, a facile strategy to synthesize oxygen and nitrogen co-doped porous carbon (ONPC) is reported by one-step pyrolysis of waste coffee grounds. As-prepared ONPC possesses highly rich micro/mesopores as well as abundant oxygen and nitrogen co-doping, which is applied to sulfur hosts as lithium/sulfur batteries’ appropriate cathodes. In battery testing, the sulfur/oxygen and nitrogen co-doped porous carbon (S/ONPC) composite materials reveal a high initial capacity of 1150 mAh·g−1 as well as a reversible capacity of 613 mAh·g−1 after the 100th cycle at 0.2 C. Furthermore, when current density increases to 1 C, a discharge capacity of 331 mAh·g−1 is still attainable. Due to the hierarchical porous framework and oxygen/nitrogen co-doping, the S/ONPC composite exhibits a high utilization of sulfur and good electrochemical performance via the immobilization of the polysulfides through strong chemical binding.

Three-dimensional ZnO nanorod arrays on flexible high surface area carbon cloth were successfully synthesized and directly used as negative electrodes for lithium-ion batteries without using any binder additive. The structure and morphology of the as-prepared hybrid ZnO electrode were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). When tested as anodes in a lithium cell, the hybrid electrode demonstrated a high discharge capacity along with excellent rate capability and good cycling stability, delivering a reversible capacity of 891 mAh g−1 at the second cycle and retaining a capacity of 469 mAh g−1 after 100 cycles.