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Investigating the factors that influence resistance rise of PIM-1 membranes in nonaqueous electrolytes

https://doi.org/10.1016/j.elecom.2019.106530Get rights and content
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Highlights

  • PIM-based membranes undergo resistance rise when used in nonaqueous flow batteries.

  • Low electrolyte flow rate and solvent prewashes reduce the rate of resistance rise.

  • Resistance rise is not associated with irreversible chemical and structural changes.

  • Membrane performance can be recovered by ex-situ and in-situ solvent washes.

Abstract

As redox active macromolecules are introduced to the materials repertoire of redox flow batteries (RFBs), nanoporous membranes, such as polymers of intrinsic microporosity (PIMs), are emerging as a viable separation strategy. Although their selectivity has been demonstrated, PIM-based membranes suffer from time-dependent resistance rise in nonaqueous electrolytes. Here, we study this phenomenon as a function of membrane thickness, electrolyte flow rate, and solvent washing using a diagnostic flow cell configuration. We find that the rate and magnitude of resistance rise can be significantly reduced through the combination of low electrolyte flow rate and solvent prewash. Further, our results indicate that, since the increase is not associated with irreversible chemical and structural changes, the membrane performance can be recovered via ex-situ or in-situ solvent washes.

Keywords

Energy storage
Redox flow battery
Polymer of intrinsic microporosity
Size-exclusion membranes
Performance recovery
Cell resistance

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