Sodium-ion battery (SIB) is especially attractive in cost-effective energy storage device as an alternative to lithium-ion battery. Particularly, metal phosphides as potential anodes for SIBs have recently been demonstrated owing to their higher specific capacities compared with those of carbonaceous materials. Unfortunately, most reported metal phosphides consist of irregular particles ranged from several hundreds nanometers to tens of micrometers, thus delivering limited cyclic stability. This paper reports the sodium storage properties of additive-free Cu₃P nanowire (CPNW) anode directly grown on copper current collector via an in situ growth followed by phosphidation method. Therefore, as a result of its structure features, CPNW anode demonstrates highly stable cycling ability with an ≈70% retention in capacity at the 260th cycle, whereas most reported metal phosphides have limited cycle numbers ranged between 30 and 150. Besides, the reaction mechanism between Cu₃P and Na is investigated by examining the intermediate products at different charge/discharge stages using ex situ X-ray diffraction measurements. Furthermore, to explore the practical application of CPNW anode, a pouch-type Na⁺ full cell consisting of CPNW anode and Na₃V₂(PO₄)₃ cathode is assembled and characterized. As a demonstration, a 10 cm × 10 cm light-emmiting diode (LED) screen is successfully powered by the Na⁺ full cell.

In the quest to develop next generation lithium ion battery anode materials, satisfactory electrochemical performance and low material/fabrication cost are the most desirable features. In this article, porous Si nanowires are synthesized by a cost-effective metal-assisted chemical etching method using cheap metallurgical silicon as feedstock. More importantly, a thin oxide layer (≈3 nm) formed on the surface of porous Si nanowires stabilizes the cycling performance of lithium ion batteries. Such an oxide coating is able to constrain the huge volume expansion of the underlying Si, yet it is thin enough to ensure good permeability for both lithium ions and electrons. Therefore, the extraordinary storage capacity of Si can be well retained in prolonged electrochemical cycles. Specifically, Si/SiO_x nanowires deliver a reversible capacity of 1503 mAh g⁻¹ at the 560th cycle at a current density of 600 mA g⁻¹, demonstrating an average of only 0.04% drop per cycle compared with its initial capacity. Furthermore, the highly porous structure and thin Si wall facilitate the electrolyte penetration and shorten the solid-state lithium transportation path, respectively. As a result, stable and satisfactory reversible capacities of 1297, 976, 761, 548, and 282 mAh g⁻¹ are delivered at current densities of 1200, 2400, 3600, 4800, and 7200 mA g⁻¹, respectively.