Unprecedented Impact of Main Chain on Comb Polymer Electrolytes Performances

Abstract

Comb‐like polymers are one of the most auspicious candidates for building fully amorphous and highly conductive solid polymer electrolytes (SPEs), which are essential components to develop high‐performance solid‐state rechargeable lithium metal batteries (RLMBs). Herein, two kinds of comb‐like polymers containing either polymethacrylate or polyacrylate as main chains are comparatively investigated, aiming to illustrate the role of polymer backbones on the basic properties of SPEs. The comb‐like SPEs are fully amorphous, and exhibit significantly higher ionic conductivities at room temperature over traditional poly(ethylene oxide) (PEO)‐based ones (close to 10−4 S cm−1). In particular, the polymethacrylate‐based SPEs show significantly improved interfacial stability against lithium metal electrode compared with the polyacrylate‐based ones, due to the elimination of electrochemically labile C−H moiety at the alpha position of the carbonyl group (C=O) in the polyacrylate structure. The present work provides not only a new family of SPEs consisting of lithium bis(fluorosulfonyl)imide (LiFSI) and poly(methoxy‐polyethylene glycol methacrylate) (i.e., LiFSI/P(CH3‐MPEGMA)), with high ionic conductivities at room temperature but also insights into developing lithium‐metal‐friendly SPE for safe RLMBs.

Anion Donicity of Liquid Electrolytes for Lithium Carbon Fluoride Batteries

“…Similar phenomenon is also evidenced in the comb-like polymer, i.e., the P(CH 3 -MPEGMA) with larger volume of CÀ CH 3 vs. CÀ H moieties adjacent to carbonyl group (C(CH 3 )À C vs. CHÀ C) could inhibit structural re-arrangement of polymer chains, thus eliminating ordered regions. [30] Under the same conditions, the bare DME shows only a sharp melting transition at À 64 °C without other thermal events, which indicates that the skeleton of DME is relatively flexible and is reluctant to be a glass former. [31] Such scenarios change drastically when turning into the solvent mixture.…”

Ion transport and structural design of lithium-ion conductive solid polymer electrolytes: a perspective

“…The design of the molecular structures of polymer matrices is one of the most effective methods to boost the ionic conductivity at room temperature and anti-oxidation properties of PEO-based SPEs [53,87,[94][95][96][97]. Here, the research progress related to some emerging polymer matrices is discussed in the following section, including (a) Jeffamine-based amorphous polymers, and (b) polycarbonate and its derivatives.…”

Grafted Copolymer Electrolytes Based on the Poly(acrylic acid-co-oligo ethylene glycol acrylate) (P(AA-co-OEGA)) Ion-Conducting and Mechanically Robust Block

“…Furthermore, a significant decrease of PEO crystallinity on going from linear to comb-like architecture was reported for PS- b -PEO diblock copolymers . Hence, the grafted architecture with a comb-like chain topology is advantageous over linear ones for designing fully amorphous SPEs. − …”

“…However, the main factor that impedes ion transport in copolymers based on linear chains of PEO is the strong tendency for crystallization, as well as the formation of crystalline complexes with certain Li salts. Attempts have been made to suppress the crystallinity mainly by modifying the polymer architecture (e.g., grafted architecture, − tapered copolymers − ). Parenthetically, tapered copolymers combine nanostructured morphologies (double gyroid, cylindrical or perforated layers) favorable for Li-ion transport, with improved segmental mobility and excellent mechanical properties (toughness and strain at break exceeding 900%) as compared to their normal copolymers. − Moreover, the tendency for crystalline complex formation can be tuned by changing the lithium salt.…”

“…A promising comb-like (branched-like) homopolymer electrolyte that combines the grafted architecture and the beneficial characteristics of PEO is the poly­(oligo ethylene glycol methacrylate) (POEGMA). − POEGMA and its acrylic analogue poly­(oligo ethylene glycol acrylate) (POEGA) have the advantage of being biocompatible. As such, they have been employed in drug delivery applications. − Specifically, POEGMA (POEGA) consists of a methyl meth­(acrylate) backbone and ethylene glycol side groups.…”