Interfacial and Ionic Modulation of Poly (Ethylene Oxide) Electrolyte Via Localized Iodization to Enable Dendrite‐Free Lithium Metal Batteries

Abstract

Solid polymer electrolytes (SPEs) make contact with highly reductive lithium (Li) metal anodes, forming the interphase that largely determines the battery performance. In this work, trace iodine doping in a poly(ethylene oxide) (PEO) electrolyte to achieve a stable interphase on Li metal surface for long battery cycling, is proposed. The triiodide ion (I3−) stemming from iodine additives can coordinate with the COC bond of PEO to enable the increased ionic conductivity of the SPE. The I‐doped interphase contains I3− and IO3−, which spontaneously react with the dead Li and Li2O at the initial interphase to smooth the Li metal surface, eventually leading to significant improvements in interfacial resistance and dendrite suppression. When matching with the LiFePO4 cathode, the full cell exhibits higher capacity (150 mAh g−1) and excellent cycling stability after 300 cycles (capacity retention of 96.5%) at 0.5 C and 50 °C. This work opens up a promising avenue for using halogen to design solid‐state Li metal batteries.

Tuning Ion/Electron Conducting Properties at Electrified Interfaces for Practical All‐Solid‐State Li–Metal Batteries

“…Performance of various PEO-based SSEs. a) Schematic representations of ideal PEO-based SSEs; b) Temperature-dependent ionic conductivity of the PEO-based SSEs; c) Ionic conductivity of different content ND in the PEO-based SSEs at 30, 40, 50, 60, and 70 °C; d) Electronic conductivity of various PEO-based SSEs; e) LSV curves of various PEO-based SSEs; f) Comparison of the performance of PEO-based SSEs as per our data and previous reports [9,16,21,29].…”

“…Besides, the Li + transference number (t Li + ) of ND-PEO SSE also showed a slight increasement under the mediation of NDs (Figures S6 and S7, Supporting Information). [9,16,21,29] According to previous works, high electronic conductivity of SSE will not only lead to growth of Li-metal dendrites insides the SSE, but also lead to degradation of PEO at high-voltage cathode side. Figure 1d shows the electronic conductivity of the three kinds of PEO-based SSEs.…”

Boosting Cathode Activity and Anode Stability of Zn‐S Batteries in Aqueous Media Through Cosolvent‐Catalyst Synergy

“…The 1 H chemical shift of G4-I 2 is increased compared to that of pure G4, which could be attributed to the coordination between G4 and I 3 À through the polar À COCÀ group. [24,25] In general, I 2 could be reduced to I À by accepting electrons from the electron-donating substitute. In this case, the polar À COCÀ group as electron donor can reduce I 2 to I À , and the resultant I À reacts with neutral I 2 to form I 3 À polyanions.…”

Strategies and characterization methods for achieving high performance PEO-based solid-state lithium-ion batteries

“…Tao et al demonstrated localized iodization at the anode–electrolyte interface to promote interfacial lithium diffusion. 48 I 2 was added and reacted with PEO chains, enabling the spontaneous formation of a triiodide ion (I 3 − ). The compact and uniform iodine-containing SEI layer contributed to the elevated rate performance.…”