Nickel Fluoride Nanorods as Anode Materials for Li-Ion Hybrid Capacitors

Abstract

Lithium-ion hybrid capacitors (LIHCs) are considered as promising energy storage devices due to their high energy density of lithium-ion batteries and excellent power density of supercapacitors. The electrode material is the key to the performance of LIHCs. Therefore, a rod-like nanostructure of NiF 2 with a clear morphology was prepared by a simple hydrothermal method. The nanorod structure of NiF 2 shortens the transport distance of lithium ions and provides more active sites, thus showing excellent electrochemical performance. The specific capacity of the NR-NiF 2 electrode can reach 379 mA h g −1 after 500 cycles at 0.1 A g −1 and remains at 61 mA h g −1 after 10,000 cycles (a current density of 2 A g −1 ). Meanwhile, according to the fitting results of the peak current and sweep rate, b = 0.95 is obtained, indicating that the electrochemical behavior of the NR-NiF 2 material is dominated by pseudocapacitance. Furthermore, the LIHCs of NR-NiF 2 //AC are constructed and exhibit a high energy density of 87 W h kg −1 (at 96 W kg −1 ), a high power density of 6079 W kg −1 (at 27 W h kg −1 ), and an excellent cycle stability (capacity retention of 69% after 5000 cycles at 1 A g −1 ). Hence, NiF 2 nanorods with fast kinetic properties are a promising choice as an anode material for LIHCs.

In‐suit synthesis of FeP/C/CNT composites with excellent performance in supercapacitors and lithium‐ion batteries

“…In addition, as shown in Figure 7f, the capacity retention of the asymmetric supercapacitor Ni 2 P@C/CNT//FeP/C/CNT‐2 after 10,000 cycles is 61 %, indicating that the device has good cycling stability. Compared with reported capacitors such as MnF 2 //AC, [28] NR‐NiF 2 //AC, [29] Mn 3 O 4 ‐rGO//FeP@PGNPC, [30] FeP/GEM//GSM, [31] and CoP/FeP 4 , [32] Ni 2 P@C/C/CNT//FeP/C/CNT‐2 asymmetric capacitors exhibit strong energy storage performance (Table 1), which suggests that the device has potential for certain applications.…”

“…As shown in Figure 8e, the FeP/C/CNT‐2 electrode material retains 90.9 % of its initial capacity after 1000 charge/discharge cycles at a current density of 2 A g −1 and has a Coulombic efficiency of about 100 %. Meanwhile, compared with reported lithium‐ion battery anode materials such as MnF 2 , [28] NR‐NiF 2 , [29] CNTs/FeP@C‐NR, [34] FeP@CNTs [35] and FeP@rGO, [36] the FeP/C/CNT‐2 electrode material demonstrated an excellent energy storage performance (Table 2), suggesting that the FeP/C/CNT‐2 electrode material has a certain potential for application.…”

Coprecipitation Prepared High‐Performance Anode Material KMnF3 for Lithium‐Ion Capacitors

“…With continued charging and discharging, Li þ was embedded and removed continuously, which led to the rupture of the SEI film and the full contact between the KMnF 3 electrode and electrolyte, resulting in the increase of capacity; 2) after cycling, the particles of the electrode material become smaller, making more active sites available for reaction, so the subsequent capacity will increase (Figure S1, Supporting Information); and 3) lithiation leads to the self-activation of electrochemical reactions, resulting in an increase in capacity. [41,42] Table 1 compares the specific capacity of the same type of materials with that of the KMnF 3 electrode material. Proofing that KMnF 3 has a high specific capacity.…”

Current Status and Prospects of Research on Cathode Materials for Lithium-Based Thermal Batteries

“…Besides FeF 3 , NiF 2 is also a kind of widely used metal fluoride cathode material for thermal batteries, which can be obtained by hydrothermal methods. Jiao et al 107 prepared rod-like NiF 2 nanomaterials with a clear morphology by a simple hydrothermal method. The synthesis used Ni(CH 3 COO) 2 and HF as the Ni and F precursors, respectively, and was taken at 180 °C for 12 h. As a result of the promising thermal stability of metal halides, especially metal chloride materials, a simple dehydration method can be used to obtain pure materials without seriously affecting the chlorides of trace metals from which water is removed.…”