NiS₂/FeS Holey Film as Freestanding Electrode for High‐Performance Lithium Battery

Abstract

In this work, a freestanding NiS2/FeS holey film (HF) is prepared after electrochemical anodic and chemical vapor deposition treatments. With the combination of good electrical conductivity and holey structure, the NiS2/FeS HF presents superior electrochemical performance, due to the following reasons: (i) Porous structure of HF provides a large surface area and more active sites/channels/pathways to enhance the ion/mass diffusion. Moreover, the porous structure can reduce the damage from the volumetric expansion. (ii) The as‐prepared electrode combines the current collector (residual NiFe alloy) and active materials (sulfides) together, thus reducing the resistance of the electrode. Additionally, the good conductivity of HF can improve electron transport. (iii) Sulfides are more stable as active materials than sulfur, showing only a small capacity decay while retaining high cyclability performance. This work provides a promising way to develop high energy and stable electrode for Li‐S battery.

Rational Design of a Dual‐Function Hybrid Cathode Substrate for Lithium–Sulfur Batteries

“…The masses of both sponges were fixed to be 10 mg. Figure 2d apparently reveals that after 5 h of static rest, the NiS 2 -RGO sponge thoroughly decolors the Li 2 S 4 solution, in sharp contrast to the RGO sample which ends up with visible yellow color in the Li 2 S 4 solution. [50,53] Note that the existence of Ni 3+ may result from Ni 3 S 2 or partial oxidation of NiS 2 on the surface, which has also been reported in previous studies. [21] Furthermore, additional evidence for the chemical interaction between NiS 2 and Li 2 S 4 is provided by the XPS analysis on the NiS 2 -RGO sponge before and after the Li 2 S 4 adsorption test.…”

“…[21] Furthermore, additional evidence for the chemical interaction between NiS 2 and Li 2 S 4 is provided by the XPS analysis on the NiS 2 -RGO sponge before and after the Li 2 S 4 adsorption test. [42,50] After the Li 2 S 4 adsorption test, however, the Ni 2+ and Ni 3+ peaks shift around ≈0.5 eV toward lower binding energies (Figure 2f), indicating the chemical bonding between NiS 2 and Li 2 S 4 . [50,53] Note that the existence of Ni 3+ may result from Ni 3 S 2 or partial oxidation of NiS 2 on the surface, which has also been reported in previous studies.…”

“…The main peak located at 284.6 eV represents CC/CC bonding; the other three oxygen-containing peaks at 285.6, 287.5, and 288.9 eV correspond to, respectively, CO/CS, CO, and OCO. [42,50,51] Note that 163.9 eV could be also assigned to CS bonding. It could result from the removal of oxygen functional groups and possible CS bonding formation in the resulting NiS 2 -RGO sponge during hydrothermal reduction.…”

“…Such a visual comparison implies a strong affinity of sulfiphilic NiS 2 to Li 2 S 4 as compared to the nonpolar RGO possessing weak physical Li 2 S 4 absorption. [50,54] Another peak at 858.0 eV could be assigned to shakeup satellite (identified as "Sat."). In the deconvoluted Ni 2p 3/2 spectrum of the fresh NiS 2 -RGO sponge (Figure 2e), the peaks located at 854.6 and 856.3 eV can be assigned to 2p 3/2 of, respectively, Ni 2+ and Ni 3+ .…”

Self‐Supported Tin Sulfide Porous Films for Flexible Aluminum‐Ion Batteries

“…[18,20] The discharge plateau and capacity slightly decrease with increasing current densities, owing to the improved ion diffusion within the highly porous structure of SnS PF. [2] The rate capability at different current densities presented in Figure 2d shows a high specific capacity of 406 mAh g −1 in the initial cycle at a current density of 20 mA g −1 .…”