Blowing Iron Chalcogenides into Two-Dimensional Flaky Hybrids with Superior Cyclability and Rate Capability for Potassium-Ion Batteries

Abstract

Chalcogenide-based anodes are receiving increasing attention for rechargeable potassium-ion batteries (PIBs) due to their high theoretical capacities. However, they usually exhibit poor electrochemical performance due to poor structural stability, low conductivity and severe electrolyte decomposition on the reactive surface. Herein, a method analogue to "blowing bubbles with gum" is used to confine FeS2 and FeSe2 in N-doped carbon for PIBs anodes with ultrahigh cyclic stability and enhanced rate capability (over 5000 cycles at 2 A g −1 ). Several theoretical and experimental methods are employed to understand the electrodes' performance.The density functional theory (DFT) calculations showed high affinity for potassium adsorption on the FeS2 and FeSe2. The in-situ XRD and ex-situ TEM analysis confirmed the formation of several intermediate phases of the general formula KxFeS2. These phases have high conductivity and large interlayer distance, which promote reversible potassium insertion and facilitate the charge transfer. Also, the calculated potassium diffusion coefficient during charge/discharge further proves the enhanced kinetics. Furthermore, The FeS2@NC anode in a full cell also exhibits high cyclic stability (88 % capacity retention after 120 cycles with 99.9 % Coulumbic efficiency). Therefore, this work not only provides an approach to overcome several challenges in PIBs anode but also a comprehensive understanding of the mechanism and kinetics of the potassium interaction with chalcogenides.

Ultrathin‐Walled Bi2S3 Nanoroll/MXene Composite toward High Capacity and Fast Lithium Storage

“…The capacitance contribution ratios of the Bi 2 S 3 /MXene‐10 electrode are 61%, 65%, 72%, 75%, 78%, and 89% at 0.2, 0.4, 0.8, 1, 2, and 5 mV s −1 , respectively (Figure 7D), much higher than those of pure Bi 2 S 3 electrode (Figure S12, Supporting Information), indicating that the MXene nanosheets greatly enhance the lithium‐ion insertion and deinsertion processes. The galvanostatic intermittent titration technique (GITT) method was employed to investigate the detail lithium‐ion diffusion coefficient of electrodes based on the following equation [ 38 ] where τ is the limited time period, m B is the weight of active material, M B is the relative molecular mass of active material, V M is the molar volume, S is the contact area between electrode and electrolyte, ∆ E s is the steady potential difference in the plateau region, and ∆ E τ is the voltage drop between the beginning state and steady state. The lithium‐ion diffusion coefficient D Li calculated from the GITT curve (Figure 7E) is displayed in Figure 7F.…”

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

“…Recently, transition metal sulfides (such as MoS 2 , CoS, and CuS) have aroused extensive attention in view of their high theoretical capacities, decent redox reversibilities, and low‐cost. [ 14–21 ] Nevertheless, most of the metal sulfides materials exhibit inferior rate capability and rapid capacity degradation because of their poor electrical conductivity and unavoidable structure collapse incurred by repeated K‐ions insertion and extraction process. [ 18,22 ] To address above issue, constructing a hybrid structure with carbon materials has been employed as an efficient strategy to improve the comprehensive performance of electrode materials.…”

Design of Flexible Films Based on Kinked Carbon Nanofibers for High Rate and Stable Potassium-Ion Storage

“…In our experiments, S/N-KCNFs are used as the Faraday electrode and TAC as its capacitive adsorption electrode (the mass ratio of cathode/anode is 3:1), named S/N-KCNFs//TAC (Fig. S22) [ 54 ]. The schematic diagram of the foldable pouch cell is shown in Fig.…”