Resolution of the Modulus versus Adhesion Dilemma in Solid Polymer Electrolytes for Rechargeable Lithium Metal Batteries

Herein we present a solid electrolyte that adheres to the lithium surface and resists dendrite growth, both of which are needed for the development of high specific energy rechargeable batteries with lithium metal anodes. Nanostructured lamellar block copolymer electrolytes exhibit solid-like properties in the bulk, due to the presence of a randomly oriented granular structure, and liquid-like surface properties due to the formation of perpendicularly oriented lamellae at the lithium-electrolyte interface. The amount of charge that can be passed before short circuit in a symmetric lithium-polymer-lithium cell with nanostructured polystyrene- block -poly(ethylene oxide) electrolytes is larger than that obtained with homopolymer poly(ethylene oxide) electrolytes by a factor ranging from 11 to 48. Grazing incident small angle X-ray scattering confirms that the microstructure of the block copolymer near the lithium-polymer interface has a perpendicular orientation. This orientation leads to a liquid-like behavior of the polymer at the interface due to the liquid crystalline symmetry of block copolymers. This combination of bulk and surface properties enhances the resistance to dendrites while maintaining electrode-electrolyte contact.