Effect of electrolytes on electrochemical properties of MmNi(5)-based hydrogen storage alloy

Chengyuan Ni*, Huaiying Zhou, Zhongmin Wang, Qingrong Yao, Lanying Lu

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)
2 Downloads (Pure)

Abstract

The effect of electrolytes on the electrochemical properties of MmNi(3.68)Co(0.72)Mn(0.43)Al(0.17) hydrogen storage alloy electrodes has been investigated at 303 K and 273 K. Three electrolytes (EL1, EL2, EL3) were obtained by adding 2 wt%, 4 wt% and 6 wt% LiOH into the original electrolyte EO (6 M/ L KOH), respectively. The results indicate that the addition of LiOH improves the discharge capacity and cycle life at 303 K and 273 K. The highest maximum capacity and capacity retention (after 50th cycles) have been observed in electrolyte EL2. However, the high-rate dischargeability (HRD) decreases gradually from EO to EL3 at the two temperatures because of the addition of LiOH. The corrosion current I-corr from Tafel Polarization curves (TP) and the resistance of the oxide layer R-ol from electrochemical impedance spectroscopy (EIS) indicates that the alloy electrode worked in EL1 has a better anti-corrosion ability. The real surface area of the electrodes estimated with EIS analysis, decrease from 51.95 cm(2) in EO to 15.6 cm(2) in EL2, but increase to 31.59 cm(2) in EL3 after being fully activated. The additional LiOH improves the anti-pulverization ability of alloy powders, delay the loss of active elements within the alloy electrode, resulting in an inproved capacity retention of alloy electrode. Meanwhile, the electrochemical kinetics analysis suggests that the charge-transfer reaction at the interface of electrode surface and electrolyte is the rate-determining step when tested at 303 K and 273 K.

Original languageEnglish
Pages (from-to)2397-2409
Number of pages13
JournalInternational journal of electrochemical science
Volume9
Issue number5
Publication statusPublished - 1 Mar 2014

Keywords

  • Hydrogen storage alloy
  • Electrolyte
  • Pulverization characteristic
  • Capacity degradation
  • Electrochemical kinetics
  • NI-MH batteries
  • Rare-earth content
  • Impedance spectroscopy
  • Discharge behavior
  • Lioh pretreatment
  • NI/MH batteries
  • H-2 Absorption
  • Electrodes
  • Lanis
  • Temperature

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