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Single-ion conducting polyelectrolytes (SICPs) with mobile Li cation have recently gathered significant attention as an "ideal" electrolyte for safe solid-state rechargeable lithium batteries, because they eliminate salt concentration gradients and concentration overpotentials, allowing transference number (t Li+) values close to unity. In this work, a series of single ion conducting block copolymers, namely [(LiM) n -r- (PEGM) m ]- b -(PhEtM) k (A- b -B), is synthesized via reversible addition-fragmentation chain transfer (RAFT) copolymerization of 1-[3-(methacryloyloxy)propylsulfonyl]-(trifluoromethanesulfonyl)imide (LiM), poly(ethylene glycol)methyl ether methacrylate (PEGM) and 2-phenylethyl methacrylate (PhEtM) with controlled PEGM:LiM ratio, molecular weights (M n = 25.8 ÷ 85.9 kDa) and narrow polydispersity (M w /M n = 1.12 ÷ 1.21). The bulk ionic conductivity, solid-state morphology and thermal properties of block copolymers are studied as a function of their composition. Block copolymers having molecular weights in the range of 46 ÷ 63 kDa and any ratio of PEGM:LiM (from 3:1 to 7:1) tend to evolve in quasi-hexagonally-packed cylinders, while copolymers with higher molecular weights (M n > 74 kDa) and the ratio of PEGM:LiM = 5:1 and M A /M B ≤ 2.0 show lamellar phase separation. The lamellar long-range ordering in poly[(LiM 17 -r- PEGM 86)- b -PhEtM 131 ] and poly[(LiM 17 -r- PEGM 86)- b -PhEtM 194 ] results not only in the improved viscoelastic (mechanical) performance compared to parent copolymer poly[LiM 17 -r- PEGM 86 ] (complex viscosity = 2.5 × 108 mPa s and 8.7 × 104 mPa s at 25 °C, respectively), but also in the demonstration of sufficiently high ionic conductivity despite the decrease in Li+ amount (σ = 3.8 × 10−7 and 4.1 × 10−7 S/cm at 25 °C, correspondingly). The selected poly[(LiM 17 -r- PEGM 86)- b -PhEtM 131 ] further shows high t Li+ (0.96 at 70 °C) and wide electrochemical stability (4.4 V vs. Li+/Li at 70 °C), which results in reversible and stable cycling at high specific capacities (up to 150 and 118 mAh g−1 at C/20 and C/5 rates, respectively) when assembled in lab-scale truly-solid-state Li metal cells with Li/copolymer/LiFePO 4 configuration. [Display omitted] [ABSTRACT FROM AUTHOR]

To investigate the influence of anion structure on physical properties of electrolytes we used five different anions, namely (FSO 2 ) 2 N (FSI, FSA), (CN) 2 N (DCA), (CF 3 SO 2 ) 2 N (TFSI, TFSA), CF 3 SO 3 (TfO) and (CF 3 SO 2 )N(CN) (TFSAM), and investigated them in a series of polyelectrolytes, ionic liquid (IL)/Li salt mixtures and in ternary ion gels (poly(ionic liquid)/ionic liquid/Li salt), respectively. Both the poly(ionic liquid) (PIL) poly(diallyldimethylammonium) (PDADMA) and the ILs employed in the study have the same pyrrolidinium anion. To isolate solely the effect of the anion a common chloride precursor PIL was used to maintain constant the average degree of polymerization ( DP n ) and chain dispersity. The systems were analyzed in terms of ionic conductivity, electrochemical stability vs Li + /Li, ion diffusion (multinuclear Pulsed Field Gradient NMR) and local lithium ion dynamics ( 7 Li spin lattice relaxation rates). Concerning optimization of any of these parameters, different orders of the anion series are obtained and discussed in terms of structural aspects and ion coordination. In particular, the coordination strength of the –CN group to the lithium ion is higher than the coordination strength of the oxygens of the –SO 2 CF 3 fragment. As a result the lithium ion in the TFSAM samples is primarily coordinated by the –CN group. Detailed structure/property relationship analysis demonstrated that for those applications of ion gels (capacitors, sensors, etc.) where a high conductivity is a primary demand, while the electrochemical stability is not essential, the FSI anion will be the best choice. However, for energy storage systems such as Li metal batteries preferably TFSI but also TFSAM anions will represent the best compromise of relevant parameters. [ABSTRACT FROM AUTHOR]

Abstract: A series of bis(trifluoromethylsulfonyl)amide based “polymeric ionic liquids” (PILs) as high molecular mass analogues of the corresponding imidazolium, ammonium and pyrrolidinium ionic liquids (ILs) was synthesized with high purity and fully characterized including electrochemical properties. The PILs differed by the nature of the cation, the quantity of the ionic centers in each monomer repeating unit, and the alkyl length of the spacer. Two novel ionic liquid like monomers (ILMs), namely 1,3-bis(N,N,N-trimethylammonium)-2-propylmethacrylate bis(trifluoromethylsulfonyl) amide (ILM-2) and N-[(2-methacryloyloxy)-ethyl]-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (ILM-4) were synthesized and characterized. Optimal conditions for the free-radical polymerization of the ILMs were identified for the first time. It was demonstrated that, among the tested organic solvents, 1-methyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)amide IL was the best reaction medium in terms of the achievement of high polymer yields and molecular masses. For the first time, the influence of the residual monomer presence inside the PIL film on the resultant conductivity was clearly shown. The impact of the molecular mass of the PILs on the ionic conductivity was firstly studied as well. Finally, the copolymerization of ILMs with poly(ethylene glycol)dimethacrylate (PEGDM) was carried out yielding tight elastic films with the highest conductivity equal to 3.2×10−6 S/cm at 25 оС. [Copyright &y& Elsevier]