Symmetric Phthalocyanine Charge Carrier for Dual Redox Flow Battery/Capacitor Applications

Abstract

Utilizing a slurry-based symmetric charge carrier coupled with a conductive carbon additive is a promising method for developing simple, low-cost, and stable hybrid electrochemical flow systems for energy storage. Here, we used a manganese nitride 1,4,8,11,15,18,22,25-octaethoxyphthalocyanine ( EtO PcMnN; 1) as a five-redox-state symmetric charge carrier for slurry-based dual redox flow battery/ capacitor applications. Electrochemical analyses of 1 revealed a wide voltage gap, fast heterogeneous electron-transfer rates, and excellent stability toward galvanostatic cycling. Slurrystate static cell measurements utilizing 1 with a conductive carbon additive, Ketjenblack, were performed and showed high faradaic efficiency and minimal capacity fade using a glass frit porous separator.

Molecular Engineering Strategies for Symmetric Aqueous Organic Redox Flow Batteries

“…The molecules with two redox units are named double redox (DR) and can exist in three forms: fully oxidized (A), partially reduced (AH 2 ) and fully reduced (AH 4 ). Those with three redox units (28)(29)(30)(31)(32)(33)(34)(35) are named triple redox (TR) have one further stable state (AH ). We assume that all redox processes are concerted twoelectron, two-proton reactions, as is the case for most quinonelike species.…”

“…For simplicity, we report the potential values determined by the more stable isomer of AH 2 , corresponding to the largest possible ΔU. We follow the same approach for the TR molecules (28)(29)(30)(31)(32)(33)(34)(35) and choose the most stable of the three isomers of the species AH 2 and AH 4 . In molecules 1-8, where the redox units are both quinones, ΔU is considerably larger than ΔU SR .…”

Molecular Engineering Strategies for Symmetric Aqueous Organic Redox Flow Batteries

“…For simplicity, we report the potential values determined by the more stable isomer of AH 2 , corresponding to the largest possible ΔU. We follow the same approach for the TR molecules (28)(29)(30)(31)(32)(33)(34)(35) and choose the most stable of the three isomers of the species AH 2 and AH 4 . Some of the considered structures have been already proposed as RFB electrolytes.…”

High Performance Aqueous Li-Ion Flow Capacitor Realized Through Microstructure Design of Suspension Electrode

“…With the rapid growth of installed capacity of clean energy such as solar energy and wind energy, the research and development of technologies and devices suitable for large-scale energy storage has become increasingly important (Chu and Majumdar, 2012;Carbajales-Dale et al, 2014). Electrochemical storage devices based on flowable suspension-type (i.e., semi-solid) electrodes have gained much attraction in the last decade (Campos et al, 2013;Zhang X. et al, 2014;Hatzell et al, 2015;Madec et al, 2015;Liu and Zhao, 2016;Wang et al, 2016;Hou et al, 2017;Liu et al, 2017;Hunt et al, 2019;Wu et al, 2020). Similar to redox flow batteries, they usually consists of separated external reservoirs for active materials storage and a power reactor for electrochemical reaction to take place, which can offer good scalability and flexibility in application for many energy storage fields (Liu et al, 2017).…”