Building Elastic Solid Electrolyte Interphases for Stabilizing Microsized Antimony Anodes in Potassium Ion Batteries

Abstract

Alloy anodes composed of microsized particles receive increasing attention recently, which outperform the nanostructured counterparts in both the manufacturing cost and volumetric energy density. However, the pulverization of particles and fracture of solid electrolyte interphase (SEI) during cycling brings about fast capacity degradation. Herein, it is shown how normally considered fragile SEI can become highly elastic through electrolyte chemistry regulation. Compared to the SEI constructed in classic carbonate electrolyte, the atomic force microscopy tests reveal that the one built in ether‐based electrolyte doubles the maximum elastic strain to accommodate the repeated swelling‐contracting. Such an SEI effectively encapsulates the microsized Sb anodes to prevent the capacity loss from particle isolation. Coupled with an intercalation‐assisted alloying reaction mechanism, a sustained capacity of ≈573 mAh g−1 after 180 cycles at 0.1 A g−1 with outstanding initial Coulombic efficiency is obtained, which is among the highest values achieved in K‐ion batteries. This study emphasizes the significance of building robust SEI, which offers the opportunity to enable stable microsized alloy anodes.

Recent Advances and Perspectives of Battery-Type Anode Materials for Potassium Ion Storage

“…Therefore, after 180 cycles, the Sb electrode cycled in the EGDE-based electrolyte demonstrated a capacity of 573 mAh g –1 , whereas the electrode in the ECPC electrolyte completely lost its reactivity after 60 cycles (Figure g). This finding may offer insights into the formation of elastic SEIs for stabilizing alloy anodes …”

“…For example, a recent study of microsized Sb anodes found that an SEI constructed based on a KFSI/ethylene glycol diethyl ether (EGDE) electrolyte exhibited a higher elastic strain than that in a KFSI/carbonate electrolyte (ECPC), thereby demonstrating a smaller volume fluctuation (Figure 14f). 141 Therefore, after 180 cycles, the Sb electrode cycled in the EGDE-based electrolyte demonstrated a capacity of 573 mAh g −1 , whereas the electrode in the ECPC electrolyte completely lost its reactivity after 60 cycles (Figure 14g). This finding may offer insights into the formation of elastic SEIs for stabilizing alloy anodes.…”

“…(g) Cyclic performance of Sb anode under 0.1 A g –1 in different electrolytes. Reproduced with permission from ref . Copyright 2021, Wiley-VCH.…”

Engineering Pocket‐Like Graphene–Shell Encapsulated FeS2: Inhibiting Polysulfides Shuttle Effect in Potassium‐Ion Batteries

“…According to the previous reports, the SEI is mainly related to the electrolyte properties and formed mainly at the contact interface between the electrode and the electrolyte. [62,63] In FeS 2 @G@NS-3DHCs, because FeS 2 is encapsulated inside the graphene-shell (FeS 2 @G), and FeS 2 @G is embedded in the carbon matrix, so the SEI is formed mainly at the contact interface between the carbon matrix and the electrolyte. Notice that another critical role is the shuttle effect suppression of the potassium polysulfides generated during charging/discharging, which may be an important determinant for the K-storage stability.…”

Interphases in the electrodes of potassium ion batteries

“…SEI fracture can expose fresh sites for new SEI build-ups and accumulation, leading to impedance increase and structural instability of the anode [23,47]. Organic electrolytes made of K salts solvated in either ester or ether solvents are being extensively investigated for PIBs, with the focus on testing different combinations of K salts, salt concentrations and organic solvents for stable SEI formation [48][49][50]. General consideration of the generic characteristics for PIB electrolytes can be drawn based on the reported work so far.…”