Thianthrene polymers as 4 V-class organic mediators for redox targeting reaction with LiMn2O4 in flow batteries

Abstract

Redox targeting reaction is an emerging idea for boosting the energy density of redox-flow batteries: mobile redox mediators transport electrical charges in the cells, whereas large-density electrode-active materials are fixed in tanks. This study reports 4 V-class organic polymer mediators using thianthrene derivatives as redox units. The higher potentials than conventional organic mediators (up to 3.8 V) enable charging LiMn2O4 as an inorganic cathode offering a large theoretical volumetric capacity of 500 Ah/L. Soluble or nanoparticle polymer design is beneficial for suppressing crossover reactions (ca. 3% after 300 h), simultaneously contributing to mediation reactions. The successful mediation cycles observed by repeated charging/discharging steps indicate the future capability of designing particle-based redox targeting systems with porous separators, benefiting from higher energy density and lower cost.

Beyond conventional batteries: a review on semi-solid and redox targeting flow batteries-LiFePO4 as a case study

“…By keeping solid materials in the tanks, only the liquid electrolyte containing the redox mediators is being pumped. [19][20][21][22] The rst semi-solid system was proposed by Chiang and coworks using LiCoO 2 as catholyte and Li 4 Ti 5 O 12 as anolyte in carbonate electrolyte. 17 This concept combines the advantage of high energy density of lithium-ion batteries and the decoupled power and energy of redox ow batteries.…”

“…By keeping solid materials in the tanks, only the liquid electrolyte containing the redox mediators is being pumped. 19–22…”

Electrochemical recycling of polymeric materials

“…Examples of this would be electrodes with large pores which polymers could effectively diffuse into and redox mediators which could diffuse into insoluble plastic particles. 125,126 The development of novel electrolytes and the engineering of suitable electrochemical cells is equally essential. In the field of lignin valorization, the wide variety of products formed during its electrochemical oxidation has led to the development of an array of approaches to deal with selectivity issues that could inspire the plastic electrochemical recycling community.…”

Aqueous Organic Redox-Targeting Flow Batteries with Advanced Solid Materials: Current Status and Future Perspective

“…Recently, Hatakeyama-Sato et al presented 4 V-class organic polymer RMs that incorporate thianthrene derivatives, which exhibit higher potentials compared to conventional organic RMs [58]. This increased potential allows for the charging of LiMn 2 O 4 , with a significant theoretical capacity of 500 Ah/L.…”