Ion–Dipole Interaction Regulation Enables High‐Performance Single‐Ion Polymer Conductors for Solid‐State Batteries

Abstract

Solid polymer electrolytes with large ionic conductivity, high ionic transference number, and good interfacial compatibility with electrodes are highly desired for solid‐state batteries. However, unwanted polarizations and side reactions occurring in traditional dual‐ion polymer conductors hinder their practical applications. Here, single‐ion polymer conductors (SIPCs) with exceptional selectivity for Li‐ion conduction (Li‐ion transference number up to 0.93), high room‐temperature ionic conductivity of about 10−4 S cm−1, and a wide electrochemical stability window (>4.5 V, vs Li/Li+) are prepared by precisely regulating the ion–dipole interactions between Li+ and carbonyl/cyano groups. The resulting SIPCs show an excellent electrochemical stability with Li metal during long‐term cycling at room temperature and 60 °C. LiFePO4‐based solid‐state cells containing the SIPCs exhibit good rate and cycling performance in a wide temperature range from −20 to 90 °C. By the same way of ion–dipole interaction regulation, sodium‐ and potassium‐based SIPCs with both high ionic conductivity and high cationic transference numbers are also prepared. The findings in this work provide guidance for the development of high‐performance SIPCs and other metal‐ion systems beyond Li+.

Segmental Motion Adjustment of the Polycarbonate Electrolyte for Lithium-Metal Batteries

“…The electrochemical stability window of electrolytes was studied by linear scanning voltammetry (LSV). Benefiting from the high oxidation potential of SN 24 (Figure S8), the oxidation decomposition onset potentials of p-MDE-S and p-ME-S are as high as 5 V at a scan rate of 0.1 mV•s −1 , rendering a broad application prospect for high-voltage lithium-metal batteries (Figure 3d).…”

“…While pure polycarbonates are normally fragile with high Young’s modulus, such a prolonged side chain also manipulates the flexibility of the polymer to provide a mechanical stable interface for Li-metal anode. Using a solid plasticizer succinonitrile (SN) to further improve the ionic conductivity at room temperature, , stable cycling performance of the Li-metal solid cell was obtained for both LiFePO 4 and LiCoO 2 electrodes.…”

Ion Transport Kinetics in Low‐Temperature Lithium Metal Batteries

“…PEO-based electrolytes can only be used above room temperature due to the crystallization of PEO and the intimate affinity between EO chains and Li + . [69] The molecular plastic crystal succinonitrile (SN) with high polarity of nitrile groups has been introduced into PEO-based SPE to suppress its crystallization and facilitate fast Li + transport at low temperatures. [70] Recently, based on the interaction of SN and ethoxylated trimethylolpropane triacrylate (ETPTA) with polar carbonyl groups, an in situ cross-linked plastic crystal-based electrolyte (CPCE) has been proposed (Figure 7d).…”

Trace weak solvation environment enabling ultra-stable high-voltage solid-state lithium metal battery

“…35). To the best of our knowledge, the electrochemical performances of our developed Li||PDTL||NCM811 and Li||PDTL||Li cells largely outperform the other recently reported solid-state batteries 6,25,[39][40][41][42][43][44][45][46] (Fig. 4h and Supplementary Table 1).…”