Solid electrolyte membranes prepared from poly(arylene ether sulfone)-g-poly(ethylene glycol) with various functional end groups for lithium-ion battery

A series of poly(arylene ether sulfone)-g-poly(ethylene glycol)s (PAES-g-PEG)s with different functional groups of –CH₃, –OH, -2OH, and –CN were synthesized for the application of solid polymer electrolyte membranes in the lithium-ion battery. Several essential material and membrane properties, including thermal, mechanical, dimensional stability, lithium-ion conductivity, interfacial compatibility, Li-ion transference number, and cell performance, were investigated. The phase separation behavior in the presence of ionic liquid was also examined using small-angle X-ray scattering. As this provision of functional groups led to the suppression of crystallinity but the increment of dielectric permittivity of the electrolytes, both the lithium-ion conductivity and Li-ion transference number were significantly affected. Among them, the PAES-g-PEG membrane containing –CN end group showed the highest lithium-ion conductivity of 8.97 × 10⁻⁴ S cm⁻¹ and the Li-ion transference number of t_Li⁺ = 0.4, maintaining the rigid solid-state with the tensile strength beyond 1.5 MPa at room temperature. These excellent physical and electrochemical properties of solid-state electrolyte membranes led to quite a high cell capacity of over 138 mAh g⁻¹ during the 50 charge-discharge cycling tests and stable lithium stripping/plating cyclic performance during 500 cycles.