Facile Method to Prepare for the Ni2P Nanostructures with Controlled Crystallinity and Morphology as Anode Materials of Lithium-Ion Batteries

Electrochemical Characteristics of Amorphous Ni-P Electroplated Thin Film

In this study, an amorphous nickel-phosphide (Ni-P) thin film was produced by electroplating, and its possible use as the anode material of a secondary lithium battery was explored. First, by changing the electroplating conditions, we created uniform and flat Ni-P thin films that contained 16–28 at% phosphorus. An evaluation of the manufactured thin film as anode material showed that a thin film with more phosphorus content had a higher specific discharge capacity. In particular, the initial gravimetric capacity of the electrode with the highest phosphorus content (28 at%) was comparable to that of graphite, but it had three times the initial volumetric capacity. The cycling stability improved with a higher phosphorus content. It was suggested that the adhesive strength between the substrate and thin film had a greater impact on the cycling stability than the physical damage caused by the volume changes during charging and discharging. To improve the specific capacity, we formed globular electrodeposits on the surface of the thin film. As a result, a discharge capacity comparable to the theoretical capacity of Ni-P was obtained, and the rate performance was additionally improved, without reduction in the life cycle.

Metallic two-dimensional BP2: a high-performance electrode material for Li- and Na-ion batteries

Searching for high-performance electrode materials is an important topic in rechargeable batteries. Using first-principles calculations, we systematically explore the potential application of a two-dimensional BP2 monolayer as a cathode material for Li-ion and Na-ion batteries. The pristine BP2 monolayer exhibits metallic characteristics, which facilitate the transportation of electrons. The Li and Na atoms bind strongly to the BP2 monolayer, indicating a good structural stability. Furthermore, the geometrical structure of BP2 is well maintained during the adsorption process. The Li and Na ions prefer to move along the zigzag direction with relatively low energy barriers. Especially, the ultralow Na diffusion barrier (0.03 eV) implies that monolayer BP2 has an excellent charge/discharge capability. The specific capacity and average electrode potential of Li (Na) are 619.45 (279.93) mA h g-1 and 2.89 (2.49) V, respectively. These results reveal that the BP2 monolayer is an appealing cathode material for alkali-metal batteries.