Achieving superior sodium storage of FeSe2@NC composite via optimizing architecture

NiSe2 Nanoparticles Decorated on Carbon Nanosheet Arrays as Anodes for Sodium Storage

“…It is noted that the R ct values derived from the NiSe 2 /C-2G-500 and NiSe 2 electrodes quickly drop to 26 and 341 Ω after 10 cycles, signifying the significantly accelerated charge transfer ability of the two electrodes due to the initial activation and then slightly increase to 80 and 562 Ω, respectively, suggesting the relatively good interface stability. , Additionally, the D Na + values can also be calculated according to the following equation: D Na + = 0.5 R 2 T 2 / S 2 n 4 F 4 C 2 σ 2 , where the Warburg factor σ can be derived from the slope by linearly fitting Z ′ vs ω –1/2 . , From Figure D, the D Na + of the initial NiSe 2 /C-2G-500 electrode before cycling is calculated to be 1.45 × 10 –17 cm 2 s –1 , about 2.3 times that of NiSe 2 (6.36 × 10 –18 cm 2 s –1 ). After 10 cycles, the D Na + of the NiSe 2 /C-2G-500 and NiSe 2 electrodes both rapidly increase to 1.24 × 10 –12 and 2.20 × 10 –15 cm 2 s –1 , respectively, reflecting the occurrence of more open channels within the electrode materials upon the activation. , It should be mentioned that, as the cycling process further extends to 100 cycles, the NiSe 2 electrode exhibits a much decayed D Na + value of 3.83 × 10 –16 cm 2 s –1 possibly due to the agglomeration of the NiSe 2 nanoparticles, while the NiSe 2 /C-2G-500 electrode presents a continuously increased D Na + value of 5.12 × 10 –12 cm 2 s –1 , which is about 13,368 times that of NiSe 2 . The above results clearly indicate that the unique porous network structure with intimately anchored NiSe 2 nanoparticles on the supporting skeleton of carbon nanosheets can provide more open and stable channels for the penetration and migration of electrolyte ions in the composite, leading to the faster kinetics of Na + diffusion in the NiSe 2 /C-2G-500 electrode.…”

“…After 10 cycles, the D Na + of the NiSe 2 /C-2G-500 and NiSe 2 electrodes both rapidly increase to 1.24 × 10 −12 and 2.20 × 10 −15 cm 2 s −1 , respectively, reflecting the occurrence of more open channels within the electrode materials upon the activation. 82,83 It should be mentioned that, as the cycling process further extends to 100 cycles, the NiSe 2 electrode exhibits a much decayed D Na + value of 3.83 × 10 −16 cm 2 s −1 possibly due to the agglomeration of the NiSe 2 nanoparticles, while the NiSe 2 /C-2G-500 electrode presents a continuously increased D Na + value of 5.12 × 10 −12 cm 2 s −1 , which is about 13,368 times that of NiSe 2 . The above results clearly indicate that the unique porous network structure with intimately anchored NiSe 2 nanoparticles on the supporting skeleton of carbon nanosheets can provide more open and stable channels for the penetration and migration of electrolyte ions in the composite, leading to the faster kinetics of Na + diffusion in the NiSe 2 /C-2G-500 electrode.…”

FeSe2 Graphite Intercalation Compound as Anode Materials for Sodium Ion Batteries

“…Nonmetallic elements, namely, oxygen (O), sulfur (S), phosphorus (P), and selenium (Se), have a higher theoretical capacity when used as negative materials for sodium ion conversion. − Among these elements, selenium (Se) has a higher electrical conductivity of 10 –3 S m –1 compared to oxygen (O) with a conductivity of 10 –5 S m –1 and sulfur (S) with a conductivity of 10 –28 S m –1 . , In addition, selenium has a larger atomic radius, which increases its tendency to lose electrons. − FeSe 2 is a promising negatively polar material for SIBs because of its excellent electrical conductivity, , remarkable theoretical capacity, chemical stability, and nontoxic properties. However, similar to other conversion materials, − FeSe 2 exhibits significant volume expansion and experiences substantial capacity degradation during cycling.…”

“…22,23 In addition, selenium has a larger atomic radius, which increases its tendency to lose electrons. 24−26 FeSe 2 is a promising negatively polar material for SIBs because of its excellent electrical conductivity, 27,28 remarkable theoretical capacity, 29 chemical stability, and nontoxic properties. However, similar to other conversion materials, 30−32 FeSe 2 exhibits significant volume expansion and experiences substantial capacity degradation during cycling.…”

Ultrafast and ultrastable FeSe2 embedded in nitrogen-doped carbon nanofibers anode for sodium-ion half/full batteries

“…Among them, FeSe 2 has attracted much attention in view of its abundant resources and satisfactory theoretical capacity [23,24]. Unfortunately, the FeSe 2 particles as anode materials exhibit low intrinsic conductivity, particle aggregation, and huge volume change during charging/discharging process, resulting in poor rate and cycling performance [25][26][27]. To address these challenges, designing nanostructured composites with carbon-based materials have been made to alleviate the volume expansion and improve the conductivity [28][29][30][31][32].…”