Ce2(SO4)3 was used as electrolyte for hybrid asymmetric energy storage devices.
Mass balance of the electrodes allowed the cell voltage to be increased up to 1.9 V.
The use of a cation-exchange membrane improved the performance of the system.
Energy density values of ∼20 W h kg−1 were achieved.
The optimized devices showed a good long-term behavior over 20,000 cycles.