Water‐Soluble Salt Template‐Assisted Anchor of Hollow FeS₂ Nanoparticle Inside 3D Carbon Skeleton to Achieve Fast Potassium‐Ion Storage

Abstract

The rationally structural engineering is an efficient strategy to improve the comprehensive performance of potassium‐ion storage anode materials. In this paper, a hybrid with hollow FeS2 nanoparticles anchored into the 3D carbon skeleton (labeled as H‐FeS2@3DCS) is successfully constructed through two critical steps of in situ chemical deposition and anion‐exchange reaction strategies. In the former, the water‐soluble Na2CO3 crystals are used as hard templates for the preparation of 3DCS, while Fe3+‐containing aqueous solutions are utilized to remove the Na2CO3 templates. Interestingly, the intense collision between Fe3+ and CO32‐ in aqueous solution produces nanoscale Fe(OH)3 colloidal particles, which are firmly anchored into the pores of the carbon skeleton to form a “lotus‐seed”‐like nanostructure. In the latter case, a central void space is created inside the FeS2 nanoparticles due to the different diffusion rates of S‐anions and Fe‐cations during the subsequent sulfidation process. Thanks to this unique composition model, the H‐FeS2@3DCS hybrid not only alleviates the volume expansion efficiently by rationally hollow structure design, but also provides spacious “roads” (3D carbon skeleton) and “houses” (hollow FeS2 nanoparticles) for fast K‐ion transition and storage. As the anode of PIBs and PIHCs, the resultant H‐FeS2@3DCS electrode delivers an obviously enhanced K‐ions storage performance over state‐of‐the‐art.

A novel strategy for encapsulating metal sulfide nanoparticles inside hollow carbon nanosphere-aggregated microspheres for efficient potassium ion storage

“…5c shows peaks corresponding to K–S bonds, S-doping in carbon, and oxidized sulfur species (SO x ). 43–45 SO x species may have formed because of electrolyte decomposition, which has also been observed in other ex situ studies. 50 The K 2p spectrum shown in Fig.…”

“…5d) revealed several peaks corresponding to the Fe–S and K–S bonds in the K x FeS 2 material, S-doping in carbon, and SO x -related materials. 43–45 The normalized intensity of the K 2p spectrum for the charged state, shown in Fig. 5f, was much smaller than that of the discharged state, which may be due to the decomposition of some SEI layers.…”

“…44 Finally, the peaks at the highest binding energies of 168.0 and 169.5 eV, can be assigned to the SO x phase, which has been formed from surface oxidation. 45 The C 1s XPS spectrum (Fig. 3e) can be deconvoluted into four peaks corresponding to the C–C, C–S, CO, and OC–O bonds centered at 284.5, 285.5, 288.4, and 291.3 eV, respectively.…”

Self-templated construction of peanut-like P3-type K0.45Mn0.5Co0.5O2 for highly reversible potassium storage

“…5–9 Compared with SIBs, PIBs are more likely to possess high energy density because the redox potential of K/K + (−2.93 V) is lower than that of Na/Na + (−2.71 V) and close to that of Li/Li + (−3.04 V), and seem to be the most promising alternative to LIBs in the large-scale energy storage field. 10–14 Notably, extensive research has been reported to explore high-performance anode materials, such as carbonaceous materials, 15–18 MXenes, 19 transition metal sulfides, 20–23 and alloys. 24–28 Compared with the widely available anode materials, only a limited amount of cathode materials have been reported for PIBs because of rigorous intercalation conditions arising from the larger size of K + .…”

Enhancing Potassium Storage Performance in VO2/V2O3@C Nanosheets by Synergistic Effect of Oxygen Vacancy and C‐O‐V Bond

“…Hence, the pseudocapacitive effect (k 1 v) and ions diffusion insertion process (k 2 v 1/2 ) can be calculated by ascertaining the constants of k 1 and k 2 based on the simplified equation of i/v 1/2 = k 1 v 1/2 + k 2 . [36,37] As displayed in Figure 5c, the total capacity is dominant by the ion diffusion effect with the ratio of 20.8 % at 0.2 mV s À 1 . With an increase in the sweep rates, the percentage of capacitive-controlled behavior gradually increased and finally reached 97.1 % at 1.0 mV s À 1 .…”