Synthesis of Hard–Soft–Hard Triblock Copolymers, Poly(2-naphthyl glycidyl ether)-block-poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl glycidyl ether]-block-poly(2-naphthyl glycidyl ether), for Solid Electrolytes

Abstract

Hard–soft–hard triblock copolymers based on poly­(ethylene oxide) (PEO), poly­(2-naphthyl glycidyl ether)-block-poly­[2-(2-(2-methoxy­ethoxy)­ethoxy)­ethyl glycidyl ether]-block-poly­(2-naphthyl glycidyl ether)­s (PNG-PTG-PNGs), were synthesized by sequential ring-opening polymerization of 2-(2-(2-methoxy­ethoxy)­ethoxy)­ethyl glycidyl ether and 2-naphthyl glycidyl ether using a bidirectional initiator catalyzed by a phosphazene base. Four PNG-PTG-PNGs had different block compositions (f wt,PNG = 9.2–28.6 wt %), controlled molecular weights (M n = 23.9–30.9 kDa), and narrow dispersities (Đ = 1.11–1.14). Most of the PNG-PTG-PNG electrolytes had much higher Li+ conductivities than that of a PEO electrolyte (6.54 × 10–7 S cm–1) at room temperature. Eespecially, the Li+ conductivity of PNG18-PTG107-PNG18 electrolyte (9.5 × 10–5 S cm–1 for f wt,PNG = 28.6 wt %) was comparable to one of a PTG electrolyte (1.11 × 10–4 S cm–1). The Li+ conductivities of PNG-PTG-PNG electrolytes were closely correlated to efficient Li+ transport channels formed by the microphase separation into soft PTG and hard PNG domains.

Development of the PEO Based Solid Polymer Electrolytes for All-Solid State Lithium Ion Batteries

“…Lee et al synthesized triblock copolymers based on poly(ethylene oxide) (PEO), poly (2-naphthyl glycidyl ether)–block–poly [2-(2-(2-methoxyethoxy)ethoxy) ethyl glycidyl ether]-block-poly(2-naphthyl glycidyl ether)s (PNG–PTG–PNGs) shown in Figure 1, which maintained high ion conductivity at room temperature due to the low T g (about −65 °C) and amorphous nature of the PTG blocks. It is worthy of note that the ion conductivity of the PNG 18 –PTG 107 –PNG 18 can still reach 9.5 × 10 −5 S·cm −1 , even though the fraction of amorphous regions was reduced owing to the crystalline PNG domains resulting from the formation of excellent Li + transport pathways driven by the microphase separation of PNG–PTG–PNGs [38]. Moreover, the degradation temperatures at 5 wt % loss values ( T d , 5%) of PNG–PTG–PNGs were in the range 371−390 °C, implying that solid electrolytes prepared from PNG–PTG–PNGs have a broad range of operating temperatures.…”

Tough and Flexible, Super Ion‐Conductive Electrolyte Membranes for Lithium‐Based Secondary Battery Applications

“…Moreover, the combination of a soft PTG block between two hard PNG blocks increased the thermal stability in a broad range of operating temperatures (371–390 °C). [ 200 ]…”

Hyperbranched Poly(Glycidol)‐Grafted Silica Nanoparticles for Enhancing Li‐Ion Conductivity of Poly(Ethylene Oxide)

“…The methods used for inhibiting crystallization in PEO are: changing the structure of PEO to a hyperbranched or grafted structure, forming block copolymer with a hard segment, blending with an inorganic substance or another polymer, and adding a plasticizer or nanofiller. [ 13,14 ] Moreover, phase separation of hard and soft segments in block copolymers form ion‐conductive channels with an amorphous phase, thereby augmenting the ionic conductivity of the electrolytes . [ 14–16 ] Besides, the amount of lithium salt significantly affects the segmental motion of the polymer, and controlling salt concentration, also affects the ionic conductivity.…”

“…[ 13,14 ] Moreover, phase separation of hard and soft segments in block copolymers form ion‐conductive channels with an amorphous phase, thereby augmenting the ionic conductivity of the electrolytes . [ 14–16 ] Besides, the amount of lithium salt significantly affects the segmental motion of the polymer, and controlling salt concentration, also affects the ionic conductivity. [ 17 ]…”