Unveiling True Limits of Electrochemical Performance of Organic Cathodes in Multivalent Batteries through Cyclable Symmetric Cells

Multivalent batteries are often hyped as a next-generation high-energy density battery technology, but in reality, both literature reports and practical research are plagued by poor reproducibility of electrochemical results. Within the present work, we take a look at the electrochemical testing of organic cathodes that can be used with a variety of mono- and multivalent cations and propose a cyclable symmetric cell approach, already applied to the field of lithium-ion batteries. By using a model organic system based on poly(anthraquinonyl sulfide) (PAQS) active material, we demonstrate that the symmetric cell approach elegantly removes the limitations of multivalent metal anodes, and for the first time, reveals the full potential of organic cathodes in multivalent batteries. Furthermore, symmetric cells enable reliable EIS measurements on organic cathodes and open a pathway to optimize electrochemical/transport parameters through the design of next-generation organic cathode materials and advanced electrode design(s). We suggest that the cyclable symmetric cell approach should be generally applicable in multivalent and all other batteries where electrochemical characterization requires the elimination of the counter electrode contribution.