Comparison of single-ion-conductor block-copolymer electrolytes with Polystyrene-TFSI and Polymethacrylate-TFSI structural blocks

Abstract

A new family of single-ion-conductor block-copolymer electrolytes (BCEs), comprising poly(ethylene oxide) (PEO) as conducting block and poly(styrene sulfonyl(trifluoromethanesulfonyl) imide of lithium) (PSTFSI) as structural block, was developed recently. To evaluate the influence of the structural blockon the physico-chemical and electrochemical properties, we compare two single-ion-conductor BCE families with structural blocks made of either PSTFSI or poly(3-sulfonyl(trifluoromethanesulfonyl) imide propyl methacrylate of lithium) (PMATFSI). Small-angle X-ray scattering revealed that at temperatures lower than the PEO block melting temperature, the morphology of both families is lamellar whereas, at higher temperatures, the electrolytes are in a disordered state. Both electrolyte families present an ionic conductivity maximum for some weight fraction of the structural block (w BTFSI ), named BTFSI. For w BTFSI > 0.17, the ionic conductivity of the PMATFSI-based electrolytes is larger than that of the PSTFSI-based electrolytes by at least a factor of two. Based on a detailed transport analysis, we show that the strong increase of the glass transition temperature is the main factor limiting the ionic conductivity. We also interpret the conductivity maximum of the PSTFSI-based electrolytes by a limitation in available free charges for w PSTFSI > 0.17 while the polymer dynamics slows down. The optimization of the ionic transport in this type of single-ion-conductor BCE requires promoting the compatibility of the Li þbearing structural block with the conducting block.

Enhanced ion conductivity of poly(ethylene oxide)‐based single ion conductors with lithium 1,2,3‐triazolate end groups

“…Furthermore, PEO‐based SICs with different architectures have been synthesized. The majority of studies focus on linear PEOs with single ionic end groups, but block and graft copolymers with single ion functionality as well as polymer blends of linear SICs with other polymers have been described in literature. Nevertheless, the biggest disadvantage of PEO‐based SICs is their rather low ion conductivity (≤10 −6 S cm −1 ) because of the incomplete dissociation of the ionic functionality that limits commercial applications in electrochemical devices.…”

Poly(ethylene oxide)‐based block copolymer electrolytes for lithium metal batteries

“…(e)), PEO‐ b ‐P(LiSTFSI) (Fig. (f)), P(LiMTFSI)‐ b ‐PEO‐ b ‐P(LiMTFSI) (LiMTFSI: lithium 1‐[3‐(methacryloyloxy)‐propylsulfonyl]‐1‐(trifluoromethanesulfonyl)imide) (Figs (g) and (h)) and POEM‐ b ‐P(LiMTFSI) (Fig. (i)) .…”

Expanding the chemistry of single‐ion conducting poly(ionic liquid)s with polyhedral boron anions

“…Subsequent studies were further focused on charge delocalization by bonding of electron‐withdrawing groups to sulfonate fragment (Scheme , 4 , 5 , 6 ). Afterwards came the era of SICs incorporating anions structurally similar to the well‐known bis(trifluoromethylsulfonyl)imide (TFSI) ion (Scheme , 7 , 8 , 9 , 10 , 12 ). This was later extended by the development of PILs bearing the so‐called ‘super‐TFSI’ anion (Scheme , 11 ).…”

“…Furthermore, it was revealed that to increase the ion conductivity it is preferable to place the anion in the side chain rather than in polymer backbone (Scheme , 7 , 9 , 11 , 12 ). The longer the spacer between the attached anion and main polymer chain the higher is the conductivity (Scheme , 7 , 8 ).…”

“…The longer the spacer between the attached anion and main polymer chain the higher is the conductivity (Scheme , 7 , 8 ). The transfer from random copolymers to complex macromolecular architectures (block or triblock copolymers) using reversible addition–fragmentation chain transfer or nitroxide‐mediated polymerization allowed an increase ion mobility and the realization of ionic conductivity in the solid state as high as 3 × 10 −6 S cm −1 .…”