Facile synthesis and electrochemical performance of the nanoscaled FeP anode

Abstract

Fe-P alloys with high phosphorous content have been targeted as promising anode materials because of their high theoretical capacity. However, the synthesis and cycling performance remain great challenges. Hereby FeP y (3≤y≤4) nanoparticles are facilely synthesized through a dry mechanochemical method by reacting iron and red phosphorus powders in an inert atmosphere. The morphology and crystal structure of this material are characterized by SEM and XRD, respectively, while the electrochemical performance is evaluated by a number of different techniques. The 1 st and 2 nd discharge capacity of FeP y reaches 1984 mAh/g and 1486 mAh/g, respectively, and after 10 cycles at 0.03 mA cm-2 (20 mA g-1 , 0.03 C), the capacity remains 1089 mAh/g with a coulombic efficiency of 97%, much higher than the reported results to date. The cyclability of this material becomes fairly better at a higher current density, but the specific capacity is lower compared to that of the smaller current density. By adding fluoroethylene carbonate (FEC) to the electrolyte, the cycling performance of this material was improved. The EIS analysis has also been performed in order to better understand the capacity fade mechanism of FeP y .

Enhanced electrochemical performance and decreased strain of graphite anode by Li2SiO3 and Li2CO3 co-modifying

“…However, GS41 greatly increases the redox peak density as well as retards the decrease of cathodic peak intensity and the increase of potential difference ΔE, indicating the improved reaction activity and decreased polarization. [34,35] Therefore, co-modification by Li 2 SiO 3 and Li 2 CO 3 greatly decreases the polarization and increases the electrode reaction activity of the pristine graphite, consistent with the above charge/discharge testing results.…”

“…As for all the samples at various current rates, ball milling and heat treatment decreases the capacities of the pristine graphite at high current rates, and the capacities and Coulombic efficiencies of the GS41 by only Li 2 SiO 3 and Li 2 CO 3 co-modifying are the highest, while that of the samples of GS51 and GS31 with Li 2 SiO 3 , Li 2 CO 3 and Li 4 SiO 4 residue co-modification decrease differently in spite that they are still higher than that of the pristine graphite, indicating that the improvement of capacities and reversibility of graphite is from Li 2 SiO 3 and Li 2 CO 3 , not the ball milling and thermal treatment. The as-synthesized Li 4 SiO 4 without ball-milling and heat treatment has low capacities and poor cyclability, and the initial 10reversible capacity is only 36.6 mAh g -1 and the corresponding Coulombic efficiency is as low as about34.7% at the current rate of 0.2 C besides a quick fade, as shown in…”

Monodispersed Carbon-Coated Cubic NiP2 Nanoparticles Anchored on Carbon Nanotubes as Ultra-Long-Life Anodes for Reversible Lithium Storage

“…Figure a shows Nyquist plots of the NiP 2 @C-CNTs anode collected at selected discharge/charge voltages in the first, 50th, and 100th cycle. These curves were fitted based on two kinds of equivalent circuits according to previous reports (Figure b, circuit I for open-circuit voltage (OCV) and II for the others) . The fitting results were summarized in Table .…”

“…These curves were fitted based on two kinds of equivalent circuits according to previous reports (Figure 5b, circuit I for open-circuit voltage (OCV) and II for the others). 9 The fitting results were summarized in Table 1. Plots of R s , R int , R ct , and R SEI as a function of discharge states and cycles are shown in Figure S12.…”

“…Pursuing new, safe, and low-cost electrode materials with higher capacity than currently commercialized materials has been an important mission of battery research. , As an alternative to graphite, conversion-reaction-based materials, such as oxides, fluorides, sulfides, and phosphides, have been extensively investigated as promising anode materials, due to their ability to give high capacity. Among them, metal phosphides distinguish themselves with their moderate discharge plateau and relatively low polarization, without sacrificing their advantages of capacity. − For example, the average polarization of phosphides (∼0.4 V) is lower than that of sulfides (∼0.7 V), oxides (∼0.9 V), and fluorides (∼1.1 V) . For these conversion anodes, low initial Coulombic efficiency and poor cycle stability are two important challenges for their real application. , Recent progress on compensation lithium loss on initial discharge could shed light on solving the initial Coulombic efficiency problem. − Like other phase-transformation-type electrodes ( e .…”