Low-cost hydrocarbon membrane enables commercial-scale flow batteries for long-duration energy storage

Dalian, China (SPX) Mar 29, 2022 - Flow batteries are promising for energy storage due to their high safety, high reliability, long cycle life, and high efficiency.

The development of commercial-scale flow batteries for long-duration energy storage requires to reduce the cost of flow batteries, especially the cost of ion-exchange membranes.

Recently, a research group led by Prof. LI Xianfeng from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) realized pilot-scale synthesis and roll-to-roll manufacturing of hydrocarbon membranes with high-performance in alkaline-based flow batteries.

This work was published in Joule on March 21.

The researchers realized the kilogram-level synthesis of sulfonated poly(ether-ether-ketone) (SPEEK) polymer and demonstrated the pilot-scale roll-to-roll synthesis of SPEEK membrane and their applications in alkaline-based flow batteries.

They found that the rigid skeleton and dispersive cation exchange groups enabled the high stability of the membrane in alkaline media, and could confine O-containing species (H2O, OH-, etc.) inside the membrane, resulting in the formation of continuous hydrogen-bonding networks. This favored the dissociation of H+ in H-O-H (H2O) and transfer from H2O to adjacent OH- ions through a Grotthuss mechanism, thus providing a high OH- conductivity in SPEEK.

The membrane was integrated in alkaline zinc-iron flow battery stack with power up to 4 kW, with a high energy efficiency of 85.5% operated at 80 mA/cm2.

This work was supported by the National Natural Science Foundation of China, CAS Engineering Laboratory for Electrochemical Energy Storage, and the Youth Innovation Promotion Association of CAS.

Research Report: "Low-cost hydrocarbon membrane enables commercial-scale flow batteries for long-duration energy storage"