Electroactive-zone extension in flow-battery stacks

Kyle C. Smith, Victor E. Brunini, Yajie Dong, Yet Ming Chiang, W. Craig Carter

Research output: Contribution to journalArticlepeer-review


Flowable suspensions that conduct both electrons and ions can enable the use of energy-dense electroactive species in flow batteries [M. Duduta et al., Adv. Energy Mater., 1, 511 (2011); Z. Li et al., Phys. Chem. Chem. Phys., 15, 15,833 (2013); F. Fan et al., Nano Lett., 14, 2210 (2014)]. In comparison with conventional flow batteries where electrochemical reactions are confined to a fixed current-collector region, electronically conductive flow electrodes permit electrochemical reactions to extend outside of the physical confines of the stack. We have measured and modeled how mixed-conduction enables an electroactive zone (EAZ, in which electrochemical reactions occur) that is of greater spatial extent than current collectors, the extension being termed side zone, SZ. Electrochemical reactions in SZs can reduce coulombic and energetic efficiency. Here we show that for realistic suspension properties and operating conditions, the added inefficiency is small in practice, and can be further mitigated by using appropriate operating conditions and/or materials choices. For the specific example of a non-aqueous Li4Ti5O12 suspension, we show that EAZ extension contributes less than 1% additional efficiency loss at C/10 rates for current collectors greater than 20 mm long.

Original languageEnglish (US)
Pages (from-to)460-469
Number of pages10
JournalElectrochimica Acta
StatePublished - Nov 2014


  • efficiency
  • flow battery
  • mixed-conductor
  • semi-solid suspension
  • slurry electrode

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Electrochemistry


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