Ce(OH)3 as a novel negative electrode material for supercapacitors

Novel electrode materials with desired specific capacitances are needed for supercapacitors. Rare-earth (RE)-based materials are fascinating in the field of catalysis and energy. Herein, a series of hydroxides including La, Ce, Pr and Nd was synthesized via in situ precipitation. Interestingly, only Ce(OH)3 showed a redox peak in both positive and negative ranges. The other RE hydroxides exhibited a redox peak only in the positive range. Therefore, in order to certify that Ce(OH)3 can be used as a negative electrode, symmetrical supercapacitors consisting of Ce(OH)3 as both positive and negative electrodes were assembled, and showed a voltage window of 1.3 V. Moreover, asymmetrical supercapacitors were successfully fabricated, in which the positive electrode was composed of La(OH)3, Pr(OH)3 or Nd(OH)3. These results may pave the way to novel negative electrode materials.