Rubbery Block Copolymer Electrolytes for Solid‐State Rechargeable Lithium Batteries

Abstract

For nearly 20 years, poly(ethylene oxide)-based materials have been researched for use as electrolytes in solid-state rechargeable lithium batteries. Technical obstacles to commercialization derive from the inability to satisfy simultaneously the electrical and mechanical performance requirements: high ionic conductivity along with resistance to flow. Herein, the synthesis and characterization of a series of poly(lauryl methacrylate)-b-poly[oligo(oxyethylene) methacrylate]-based block copolymer electrolytes (BCEs) are reported. With both blocks in the rubbery state (i.e., having glass transition temperatures well below room temperature) these materials exhibit improved conductivities over those of glassy-rubbery block copolymer systems. Dynamic rheological testing verifies that these materials are dimensionally stable, whereas cyclic voltammetry shows them to be electrochemically stable over a wide potential window, i.e., up to 5 V at 55ЊC. A solid-state rechargeable lithium battery was constructed by laminating lithium metal, BCE, and a composite cathode composed of particles of LiAl 0.25 Mn 0.75 O 2 (monoclinic), carbon black, and graphite in a BCE binder. Cycle testing showed the Li/BCE/LiAl 0.25 Mn 0.75 O 2 battery to have a high reversible capacity and good capacity retention. Li/BCE/Al cells have been cycled at temperatures as low as Ϫ20ЊC.

An electrochemical approach to measuring oxidative stability of solid polymer electrolytes for lithium batteries

“…These safety concerns can be reduced if a solid-state battery can be produced. Polymers doped with lithium salt have been studied for potential use as an electrolyte for lithium batteries Soo et al, 1999;Wang et al, 2003). Polymer electrolytes improve safety in several ways.…”

Recent Advancements in Polymer-Based Composite Electrolytes for Rechargeable Lithium Batteries

“…The most common architectures of BCEs are the AB di-block and the BAB tri-block, in which A is the ionic conductor block and B is the block providing other functionalities such as mechanical strength [93]. The A block in these cases generally consists of either a linear PEO block [94,95] or a low molecular weight poly(ethylene glycol) block grafted onto a macromolecular backbone such as poly(ethylene glycol methacrylate) [96]. For the mechanical reinforcement B block, a wide variety of polymers have been tested including polystyrene [94,97] and poly(alkyl meth acrylates) [96].…”

“…The A block in these cases generally consists of either a linear PEO block [94,95] or a low molecular weight poly(ethylene glycol) block grafted onto a macromolecular backbone such as poly(ethylene glycol methacrylate) [96]. For the mechanical reinforcement B block, a wide variety of polymers have been tested including polystyrene [94,97] and poly(alkyl meth acrylates) [96]. In past decade, the mechanical and morphological properties of salt-doped BCEs have attracted increasing interest, and several studies have examined the effects of salt-doping on ionic conductivity, mechanical strength and morphology [98].…”

Phase behavior and orientational ordering in block copolymers doped with anisotropic nanoparticles

“…Introduction of NPs can also improve mechanical, thermal, and dielectric properties of composite polymer nanomaterials based on block copolymers [25][26][27][28][29][30][31]. Microphase separation in block copolymers can stabilize spatially inhomogeneous NP distribution which paves the way for the design of materials to be used as smart membranes and in nanophotonics.…”