Zinc–cerium battery

[1][2] In this rechargeable battery, both negative zinc and positive cerium electrolytes are circulated though an electrochemical flow reactor during the operation and stored in two separated reservoirs.

Due to the high standard electrode potentials of both zinc and cerium redox reactions in aqueous media, the open-circuit cell voltage is as high as 2.43 V.[1] Among the other proposed rechargeable aqueous flow battery systems, this system has the largest cell voltage and its power density per electrode area is second only to H2-Br2 flow battery.

The main technological challenge is the control of the inefficiency and self discharge (Zn corrosion via hydrogen evolution) at the negative electrode.

In commercial terms, the need for expensive Pt-Ti electrodes increases the capital cost of the system in comparison to other RFBs.

[9][10] Because of the large cell voltage, hydrogen (0 V vs. SHE) and oxygen (+1.23 V vs. SHE) could evolve theoretically as side reactions during battery operation (especially on charging).

[12] In 2011, a membraneless (undivided) zinc–cerium system based on low acid concentration electrolyte using compressed pieces of carbon felt positive electrode was proposed.

The use of mixed acid electrolytes for the positive half-cell has been investigated as a mean to increase the kinetics of the cerium redox reaction in State Key Laboratory of Rare Earth Resource Utilization and the Jiangxi University of Science and Technology, China.

[26] This permitted to rationalise the contribution of the thermodynamic, kinetic and ohmic components of the battery voltage and to assess the effect of increasing inter-electrode gap.