Single-Ion Conducting Polymer Electrolytes Based on Random Polyurethane–Urea with Different Diisocyanate Structures for Lithium Batteries

Abstract

Polyurethane−urea ionomers based on poly(ethylene oxide) (PEO) with various hard segment contents were synthesized from diisocyanates with different symmetries and planarities. The influence of the random copolymer microphase structure (including the phase separation morphology and hydrogen bonding behavior) on the ion states and ion migration was investigated. The soft phase could maintain a low glass transition temperature to yield samples with good ionic conductivity when the hard segment was less than 48 wt %. Furthermore, the hard phase and hydrogen bonds could provide good mechanical strength. Fourier transform infrared spectroscopy and small-angle X-ray scattering confirmed that ionomers with a smaller degree of phase separation had a high fraction of ions in isolated ion pairs. Coupled with faster segmental dynamics and ion mobility from the depressed T g , the polyurethane−urea ionomer simultaneously showed high strength and ionic conductivity. After plasticization, the prepared single-ion conductor was successfully tested in lithium cells, demonstrating outstanding discharge capacity (166 mAh g −1 ), Coulombic efficiency (96.5%), and retention (92.6% after 100 cycles) at 0.1 C and high temperature.

Fast Li+ Transport Polyurethane-Based Single-Ion Conducting Polymer Electrolyte with Sulfonamide Side chains in the Hard Segment for Lithium Metal Batteries

“…The ion conductivity of the PUTA samples, except for PUTA-50, increased with the increasing ion concentration. PUTA-40, with a large content of hard segments, displayed excellent ionic conductivity, exceeding 10 –5 S cm –1 at 80 °C, which was inconsistent with our previous study . This phenomenon indicates that the nanochannels formed in the hard domains were conducive to ion transport, leading to a rapid increase in ionic conductivity.…”

“…PUTA-40, with a large content of hard segments, displayed excellent ionic conductivity, exceeding 10 −5 S cm −1 at 80 °C, which was inconsistent with our previous study. 13 This phenomenon indicates that the nanochannels formed in the hard domains were conducive to ion transport, leading to a rapid increase in ionic conductivity. Most PUTE polymers behave as viscous liquids, which limits their application in batteries.…”

“…Thermoplastic polyurethane (TPU) is regarded as an interesting polymer matrix for polymer electrolytes , because its properties can be tailored throughout a wide range by modifying its composition and structure. , Polyurethane-based SICPEs can self-assemble into a unique microphase structure with hard domains randomly dispersed in the continuous low- T g (glass transition temperature) soft phase, − allowing the antagonistic qualities of ion conductivity and mechanical strength to be combined in the same TPU material. The hydrogen bonding in the hard segments acts as a physical cross-link to provide mechanical reinforcement, whereas the strong segmental motion of the soft phase is conducive to charge transport. , Notably, compared to polyurethane, the strong bidentate hydrogen bonding and ordered hard domain of polyurea (a specific polyurethane) promote microphase separation, resulting in better modulus and elasticity of the material .…”

An Investigation of Conjugated Sulfonamide Materials as Binders for Organic Lithium-Ion Batteries

“…More recently, aromatic sulfonamides have been utilized as a novel organic cathode material for metal-ion batteries 56−59 and as ion conductors in solid-state electrolytes. 60,61 These encouraging results provide motivation to further investigate sulfonamides as a part of functional binder additives toward ongoing energy application research.…”

Single-Ion Conducting Polyurethane-Ester Solid Polymer Electrolyte Membrane toward Lithium Metal Batteries

“…Polyurethanes with ether groups, which have a unique two-phase structure, have been proposed as SICPEs to combine these two antagonistic properties. − Polyurethane (PU) is a thermoplastic multiblock copolymer. The chemical immiscibility of the unlike segments and hydrogen bonding drive the phase separation into high-glass-transition-temperature ( T g ) hard domains and a continuous low T g soft phase .…”