Controllable Synthesis of a Monophase Nickel Phosphide/Carbon (Ni₅P₄/C) Composite Electrode via Wet‐Chemistry and a Solid‐State Reaction for the Anode in Lithium Secondary Batteries

Abstract

A monophase nickel phosphide/carbon (Ni5P4/C) composite with a thin carbon shell is controllably synthesized via the two‐step strategy of a wet‐chemistry reaction and a solid‐state reaction. In this fabrication, the further diffusion of phosphorus atoms in the carbon shell during the solid‐state reaction can be responsible for a chemical transformation from a binary phase of Ni5P4‐Ni2P to monophase Ni5P4. Galvanostatic charge‐discharge measurements indicate that the Ni5P4/C composite exhibits a superior, high rate capacibility and good cycling stability. About 76.6% of the second capacity (644.1 mA h g−1) can be retained after 50 cycles at a 0.1 C rate. At a high rate of 3 C, the specific capacity of Ni5P4/C is still as high as 357.1 mA h g−1. Importantly, the amorphous carbon shell can enhance the conductivity of the composite and suppress the aggregation of the active particles, leading to their structure stability and reversibility during cycling. As is confirmed from X‐ray‐diffraction analysis, no evident microstructural changes occur upon cycling. These results reveal that highly crystalline Ni5P4/C is one of the most promising anode materials for lithium‐ion batteries.

One-pot synthesis of carbon-coated Ni5P4 nanoparticles and CoP nanorods for high-rate and high-stability lithium-ion batteries

“…[1][2] Recently, transition-metal phosphides (TMPs) are emerging as an appealing and promising class of anode materials due to their 30 abundance and high theoretical capacity for lithium storage. The high theoretical capacities of TMPs are originated from the conversion reactions with lithium to yield metallic particles and Li 3 P, [3][4][5] which leads to massive uptake of lithium before the reduced metal starts precipitating out. So, based on this 35 mechanism, the theoretical capacities of mono-phosphorus TMPs, including FeP, CoP and Ni 5 P 4 can reach 926, 895 and 767 mA h g -1 , respectively.…”

The preparation of Ni 5 P 4 /Ni composite via a chemical corrosion method and its application in lithium ion batteries

“…The sloping potential regions for the second and third discharge curves shift to high potential regions located over 2.5-0.75 and 0.75-0.02 V, which may be relevant to the activation of the electrode in the initial discharge and charge processes [7][8][9]. The initial three charge curves show similar profile with two sloping potential regions located at 0.23-1.2 and 1.2-3.0 V, corresponding to the oxidation of Ni into Ni 5 P 4 [6]. Fig.…”

“…3(a) shows the initial three charge/discharge curves of Ni 5 P 4 /Ni at a current density of 0.1 mA cm À 2 . The initial discharge curve differs much from the subsequent two, showing two sloping potential regions (1.75-0.38 and 0.38-0.02 V), which correspond to the reduction of Ni 5 P 4 and the formation of solid electrolyte interface (SEI), respectively [6]. The sloping potential regions for the second and third discharge curves shift to high potential regions located over 2.5-0.75 and 0.75-0.02 V, which may be relevant to the activation of the electrode in the initial discharge and charge processes [7][8][9].…”

“…Lu et al reported the preparation of Ni 5 P 4 /C composite, which shows potential application as anode for lithium ion batteries [6]. Here in this paper, we report the preparation of Ni 5 P 4 /Ni composite architecture via a chemical corrosion method and its electrochemical performance as anode for lithium ion batteries.…”

Lithium transition metal pnictides – structural chemistry, electrochemistry, and function

“…While a common in situ coating procedure was performed for Ni 5 P 4 (Lu et al 2012b), also graphene oxide sheets were added to Ni 2 P to improve the electrochemical performance (Lu et al 2012a,c). The in situ approach in Ni 5 P 4 /C (644 mAh g -1 , 0.1 C-rate, 50 cycles) seems to be a little more successful than the ex situ approach for Ni 2 P/graphene oxide (450 mAh g -1 , 0.1 C-rate, 50 cycles).…”