Poly(ethylenimine)-Based Polymer Blends as Single-Ion Lithium Conductors

Abstract

Highly conductive solid polymer electrolytes were generated by blending linear poly(ethyleneimine)-graftpoly(ethylene glycol) with linear poly(ethyleneimine) bearing lithium N-propylsulfonate groups as the lithium source. The effect of polymer backbone structure on Li + conductivity was determined by comparing a series of blends made from the PEI-based materials with those from polymethacrylate backbone analogues. The use of PEI backbones promoted ion-pair dissociation, stabilized the macromolecular mix and generated blends with ionic conductivities up to 2 orders of magnitude higher than those of the polymethacrylate-based systems. Blends containing the PEI-bound lithium sulfonates exhibited lithium conductivities higher than those measured for PEG doped with lithium bis(trifluoromethyl)sulfonimide. Shifts in the ν s (SO 3 ) IR absorption band suggest that the solvation environment for the lithium sulfonates changes with polymer structure. The PEI-based blends are thermally stable up to 200°C, electrochemically stable in the ±5 V range, and showed unparalleled ionic conductivities (0.4 mS/cm at room temperature and 5 mS/cm at 80°C) for solvent-free systems with polymer-bound anions.

Poly(ethylene oxide)-based electrolytes for lithium-ion batteries

“…The buildup of anions on the anode results in electropolarization, which lowering the overall performance of LIBs due to high internal resistance, voltage losses, and undesirable side reactions. 557 Single-ion conductors can overcome most of these challenges. However, the lower ionic conductivities (< 10 -5 S cm -1 ) are obtained in these single-ion systems when compared with salt-doped counterparts, which resulting from the covalent bonding of the anions to the polymer backbone and to an incomplete dissociation of the lithium salts within the polymer matrix.…”

Poly(arylene ether)-Based Single-Ion Conductors for Lithium-Ion Batteries

“…These results are one of very few examples clearly demonstrating that the prepared single-ion membrane is applicable for use in lithium-ion batteries at room temperature. 32 …”

“…29 A group of single-ion conductors comprising poly(ethylenimine)-based polymer blends has been reported to show a state-of-the-art conductivity of 4 × 10 −4 S cm −1 at ambient temperature. 32 Another class of single-ion conductors is gel polymer electrolytes, which have been reported to display ionic conductivities of 10 −6 ∼10 −3 S cm −1 at room temperature. 33−42 Watanabe et al reported a blend of polymeric lithium salts and polyether networks, which reached an ionic conductivity of 10 −4 S cm −1 when plasticized with ethylene carbonate (EC).…”

An investigation of lithium ion conductivity of copolymers based on P(AMPS‐co‐PEGMA)

“…Lithium battery electrolytes (LIBs), which are generally all dual‐ion systems, including positive and negatively charged ions. Dual‐ion systems generally have lower cation transference numbers (0.3–0.5) and movement of both the ions leads to electrode polarization . One of the main objectives behind constructing a single‐ion system is potentially eliminating the aforementioned flaws and enhancing lithium ion battery performance.…”