A Single‐Ion Conducting Network as Rationally Coordinating Polymer Electrolyte for Solid‐State Li Metal Batteries

Abstract

Solid state single‐ion conducting polymer electrolytes (SSPEs) are one of the most promising candidates for long‐life lithium‐metal batteries. However, the traditional polyanion‐type structure of SSPEs inevitably gives rise to insufficient conductivity and inferior mechanical stability, which limits their practical application. Herein, an interpenetrating single‐ion network polymer (PTF‐4EO) is fabricated by crosslinking lithium tetrakis(4‐(chloromethyl)‐2,3,5,6‐tetrafluorophenyl)borate salt with tetraethylene glycol. The unique structure enables a PTF‐4EO with weakly interacting anions and coordinating ether oxygen segments that functions as a high‐performing SSPE, that delivers a high room‐temperature conductivity of 3.53 × 10−4 S cm−1, exceptional superior lithium‐ion transference number of 0.92, wide electrochemical window > 4.8 V, and good mechanical properties. Moreover, the resultant SSPE can directly participate in constructing a favorable Janus solid electrolyte interphase, which further enhances the interfacial stability of the metallic lithium anode. The as‐assembled LiFePO4||Li solid batteries present prominent cycling stability, coulombic efficiency, and capacity retention over 200 cycles between 2.50 and 4.25 V. Furthermore, LiNi0.7Mn0.2Co0.1O2||Li pouch cells exhibit remarkable safety even under harsh conditions. This study thereby offers a promising strategy for SSPE design to simultaneously achieve high ionic conductivity and good interfacial compatibility toward practical high‐energy‐density solid‐state lithium metal batteries.

Single-Ion Conducting Polymeric Protective Interlayer for Stable Solid Lithium-Metal Batteries

“…EIS plots of the (d) Li/PVEC/Li cell with the SIPPI and (e) Li/PVEC/Li cell after cycling at 25 °C. (f) Comparison of cycle life of Li/Li symmetric cells in this work with the previously reported polymer electrolytes. ,,,,,,,− …”

Enabling High‐Voltage “Superconcentrated Ionogel‐in‐Ceramic” Hybrid Electrolyte with Ultrahigh Ionic Conductivity and Single Li+‐Ion Transference Number

“…[22] Recently, Lian et al reported an interpenetrating single-ion polymer electrolyte, fabricated by crosslinking lithium tetrakis(4-(chloromethyl)-2,3,5,6-tetrafluorophenyl) borate salt with tetraethylene glycol, which delivered a high room-temperature conductivity of 3.53 × 10 −4 S cm −1 and an exceptional superior Li-ion transference number of 0.92. [23] The scientific community is very active in finding better electrolytes and balancing safety and performance requirements, which are currently the main hurdles to be conquered to enable the next-generation batteries. Intriguingly, ionic liquids have been extensively applied for a long time, owing to their high electrical conductivity (10 −4 to 10 −2 S cm −1 at 25 °C), wide electrochemical stability window (up to 6 V), high thermal stability (up to 200-300 °C), nonvolatility and nonflammability.…”

Solid electrolytes for solid-state Li/Na–metal batteries: inorganic, composite and polymeric materials

“…103 Lately, an interpenetrating single-ion polymer electrolyte was prepared via crosslinking lithium tetrakis(4-(chloromethyl)-2,3,5,6-tetrafluorophenyl)borate salt and tetraethyleneglycol, which showed a high conductivity of 3.53 × 10 −4 S cm −1 at room temperature and a high Li-ion-transference number of 0.92. 104…”

“…103 Lately, an interpenetrating single-ion polymer electrolyte was prepared via crosslinking lithium tetrakis(4-(chloromethyl)-2,3,5,6-tetrafluorophenyl)borate salt and tetraethyleneglycol, which showed a high conductivity of 3.53 Â 10 À4 S cm À1 at room temperature and a high Li-iontransference number of 0.92. 104 Despite these advances, a solid electrolyte that possessing a superior ionic conductivity level of 10 À3 S cm À1 at 25 1C, a large cation transference number over 0.8, and a feasibility of matching simultaneously with metallic Li anodes and intercalation cathodes, has not been achieved yet.…”