Electronegativity‐Induced Single‐Ion Conducting Polymer Electrolyte for Solid‐State Lithium Batteries

Abstract

The application of solid polymer electrolytes (SPEs) is severely impeded by the insufficient ionic conductivity and low Li+ transference numbers (tLi+). Here, we report an iodine‐driven strategy to address both the two long‐standing issues of SPEs simultaneously. Electronegative iodine‐containing groups introduced on polymer chains effectively attract Li+ ions, facilitate Li+ transport, and promote the dissociation of Li salts. Meanwhile, iodine is also favorable to alleviate the strong O−Li+ coordination through a Lewis acid–base interaction, further improving the ionic conductivity and tLi+. As a proof of concept, an iodinated single‐ion conducting polymer electrolyte (IPE) demonstrates a high ionic conductivity of 0.93 mS cm−1 and a high tLi+ of 0.86 at 25 °C, which is among the best results ever reported for SPEs. Moreover, symmetric Li/Li cells with IPE achieve a long‐term stability over 2600 h through the in‐situ formed LiF‐rich interphase. As a result, Li−S battery with IPE maintains a high capacity of 623.7 mAh g−1 over 300 cycles with an average Coulombic efficiency of 99%. When matched with intercalation cathode chemistries, Li/IPE/LiFePO4 and Li/IPE/LiNi0.8Mn0.1Co0.1O2 solid‐state batteries also deliver high‐capacity retentions of 95% and 97% at 0.2 C after 120 cycles, respectively.

Enabling highly stable lithium metal batteries by using dual-function additive catalyzed in-built quasi-solid-state polymer electrolytes

“…The high t Li + of the Mg-PDOL-FEC electrolyte can be attributed to the restricted anion transference with larger volume ions, and it can effectively reduce the concentration polarization of Li + , thereby resulting in the suppressed growth of Li dendrites and improved battery performance. 20,52 The reversibility of Li plating/stripping processes in different electrolytes was investigated in symmetric Li cells. Fig.…”

Multi‐Scale Characterization Techniques for Polymer‐Based Solid‐State Lithium Batteries

“…Reproduced with permission. [58] Copyright 2022, John Wiley & Sons, Inc. XPS spectra of i) C 1s and ii) F 1s for lithium metal retrieved from LE before and after cycles. XPS spectra of iii) C 1s and iv) F 1s for lithium metal retrieved from GPE before and after cycles.…”

“…Yunhui et al. [ 58 ] prepared a poly(1,3‐dioxolane) (PDOL) electrolyte (IPE) by iodine initiation. XPS was used to compare the lithium metal interface formed by the IPE and the liquid DOL electrolyte.…”

“…For PSSLBs, XPS is very well suited to assess the chemical structure and regularity of electrode/electrolyte interface, and its horizontal and vertical compositional changes. [57] Yunhui et al [58] prepared a poly(1,3-dioxolane) (PDOL) electrolyte (IPE) by iodine initiation. XPS was used to compare the lithium metal interface formed by the IPE and the liquid DOL electrolyte.…”

“…XPS depth profiles of C 1s and F 1s for Li metal after 100 cycles with a) LE, b) IPE, c) chemical compositions of Li metal after cycling with LE and IPE on the top surface of interphases,and d) corresponding elemental compositions at different etching times. Reproduced with permission [58]. Copyright 2022, John Wiley & Sons, Inc.…”