In Situ Monitoring the Potassium-Ion Storage Enhancement in Iron Selenide with Ether-Based Electrolyte

Abstract

As one of the promising anode materials, iron selenide has received much attention for potassium-ion batteries (KIBs). Nevertheless, volume expansion and sluggish kinetics of iron selenide result in the poor reversibility and stability during potassiation–depotassiation process. In this work, we develop iron selenide composite matching ether-based electrolyte for KIBs, which presents a reversible specific capacity of 356 mAh g−1 at 200 mA g−1 after 75 cycles. According to the measurement of mechanical properties, it is found that iron selenide composite also exhibits robust and elastic solid electrolyte interphase layer in ether-based electrolyte, contributing to the improvement in reversibility and stability for KIBs. To further investigate the electrochemical enhancement mechanism of ether-based electrolyte in KIBs, we also utilize in situ visualization technique to monitor the potassiation–depotassiation process. For comparison, iron selenide composite matching carbonate-based electrolyte presents vast morphology change during potassiation–depotassiation process. When changing to ether-based electrolyte, a few minor morphology changes can be observed. This phenomenon indicates an occurrence of homogeneous electrochemical reaction in ether-based electrolyte, which results in a stable performance for potassium-ion (K-ion) storage. We believe that our work will provide a new perspective to visually monitor the potassium-ion storage process and guide the improvement in electrode material performance.

New enhancement mechanism of an ether-based electrolyte in cobalt sulfide-containing potassium-ion batteries

“…This result indicates less damage to the electrode during the cycles, speculating that the DME-KFSI electrolyte contributes to the protection of the electrode. [45][46][47] To further confirm the differences between the SEI layers, the corresponding forcedisplacement curves and their detailed analyses were obtained by AFM, as shown in Fig. 3c-f.…”

Recent Progress on Sb‐ and Bi‐based Chalcogenide Anodes for Potassium‐Ion Batteries

“…EIS spectra of FeSe 2 @RGO electrode with DME-based and EP-based electrolytes (j) before and (k) after 50 cycles. Reproduced from Ref., [78] under the terms of the CC BY 4.0 license. most of literature, amorphous chalcogens conversion reaction is lack of detailed analysis.…”

“…discharge process, which could prevent the final conversion product of K 2 Se dissolved into electrolytes to reach better performance (Figure 11c) Next, Li et al reported FeSe 2 @rGO as anode material of PIBs, and used 1 M, 5 M KFSI in DME and 1 M KFSI in EC/PC (1 : 1, v/v) marked as EP electrolyte system for testing, respectively. [78] Among them, the 1 M KFSI in DME system observed that the voltage did not reach 3 V during the first charge. It is presumed that the low concentration electrolyte could not inhibit the dissolution of polyselenides.…”

“…There are more DME(‐H) radicals in 1 M KFSI in DME, and DME(−H) radicals will form polyethers around the SEI layer during the charge‐discharge process, which could prevent the final conversion product of K 2 Se dissolved into electrolytes to reach better performance (Figure 11c) Next, Li et al . reported FeSe 2 @rGO as anode material of PIBs, and used 1 M, 5 M KFSI in DME and 1 M KFSI in EC/PC (1 : 1, v/v) marked as EP electrolyte system for testing, respectively [78] . Among them, the 1 M KFSI in DME system observed that the voltage did not reach 3 V during the first charge.…”

“…EIS spectra of FeSe 2 @RGO electrode with DME‐based and EP‐based electrolytes (j) before and (k) after 50 cycles. Reproduced from Ref., [78] under the terms of the CC BY 4.0 license.…”