Electrochemical behavior of NiCl2/Ni in acidic AlCl3-based ionic liquid electrolyte

Abstract

The electrochemical properties of nickel chloride as a cathode in basic electrolyte have been much examined, but little study has focused on those properties in acidic electrolyte. In this study, the electrochemical behavior of Al-NiCl₂ in acidic AlCl₃-EMIC ionic liquid electrolyte is investigated, confirming the reversible reaction between Ni(2) and Ni. The assembled cell delivers an initial discharge capacity of 115.0 mA h g⁻¹ at 100 mA g⁻¹, and it remains at 93.7 mA h g⁻¹ over 100 cycles, with a Coulombic efficiency of 97.9%, displaying a high specific capacity with stable cycling performance. Additionally, the degradation mechanism of this cell is verified as the dissolution of partial Ni metal generated from the reduction of NiCl₂ during discharging in the acidic electrolyte.