Octahedral/Tetrahedral Vacancies in Fe₃O₄ as K‐Storage Sites: A Case of Anti‐Spinel Structure Material Serving as High‐Performance Anodes for PIBs

Abstract

Potassium‐ion batteries (PIBs) have attracted more and more attention as viable alternatives to lithium‐ion batteries (LIBs) due to the deficiency and uneven distribution of lithium resources. However, it is shown that potassium storage in some compounds through reaction or intercalation mechanisms cannot effectively improve the capacity and stability of anodes for PIBs. The unique anti‐spinel structure of magnetite (Fe3O4) is densely packed with thirty‐two O atoms to form a face‐centered cubic (fcc) unit cell with tetrahedral/octahedral vacancies in the O‐closed packing structure, which can serve as K+ storage sites according to the density functional theory (DFT) calculation results. In this work, carbon‐coated Fe3O4@C nanoparticles are prepared as high‐performance anodes for PIBs, which exhibit high reversible capacity (638 mAh g−1 at 0.05 A g−1) and hyper stable cycling performance at ultrahigh current density (150 mAh g−1 after 9000 cycles at 10 A g−1). In situ XRD, ex‐situ Fe K‐edge XAFS, and DFT calculations confirm the storage of K+ in tetrahedral/octahedral vacancies.

Skin‐Inspired Conversion Anodes for High‐Capacity and Stable Potassium Ion Batteries

“…[31,59,60] Moreover, even under high current (Figure S16, Supporting Information) conditions, SC-Fe 1−x S could still deliver a capacity retention of 73.5% after 1000 cycles despite the rapid removal and intercalation of potassium ions that are more likely to destroy the structure. Figure 6e shows the comparison of cycle lifetime and capacity retention of SC-Fe 1−x S/ SC-Fe 3 O 4 discussed in this work with other Fe x S y -based and Fe x O y -based anodes reported in the literature, [28,31,32,34,37,61,62] and the SC-Fe 1−x S/SC-Fe 3 O 4 possess advantages in cycling lifetime and capacity retention. The above electrochemical performance indicates that after vulcanization of the skin-inspired SC-Fe 1−x S, capacity is boosted, and the cycling stability is not compromised, which verifies the electrochemical universality of the skin-inspired anode structure.…”

“…[1,2] However, LIBs used in large-scale grid energy storage have been greatly hampered by the limited reserve and uneven distribution of lithium resources on Earth. [3][4][5][6] Recently, potassium-ion batteries (PIBs) have attracted Various strategies have been explored to resolve these limitations of [25,[27][28][29][30][31][32][33][34] iron-based oxide and sulfide anode materials. The most popular strategy is to carbon coat nanostructured iron-based oxides and sulfides, forming a core-shell structure.…”

Recyclable Fe3O4/MWCNT/CNF composite nanopaper as an advanced negative electrode for flexible asymmetric supercapacitors

“…51 Aer spectral deconvolution, the tted peaks located at 709.7 and 722.8 eV correspond to 2p 3/2 and 2p 1/2 of Fe 2+ species, while the other two tted peaks at 711.4 and 724.5 eV are attributed to 2p 3/2 and 2p 1/2 of Fe 3+ species, respectively. [52][53][54] Additionally, the peak area ratio of Fe 2+ and Fe 3+ approaches 1 : 2. These results conrm that the Fe 3 O 4 / MWCNT/CNF composites were successfully prepared.…”

3D Micro‐Flower Structured BiFeO3 Constructing High Energy Efficiency/Stability Potassium Ion Batteries Over Wide Temperature Range

“…[7][8][9][10] It has become essential and pressing to explore advanced metalion batteries as an alternative. [11][12][13][14] Potassium-ion batteries (PIBs) have captured worldwide research interests due to their lithium-like electrochemical properties, abundant reserves, and relatively moderate cost. [15][16][17][18] Furthermore, K + has a lower Lewis acidity compared with Li + and Na + , demonstrating superior desolvation capability and faster ion diffusion kinetics in the electrolyte.…”