Porphyrin‐Based Symmetric Redox‐Flow Batteries towards Cold‐Climate Energy Storage

Abstract

Electrochemical energy storage with redox-flow batteries (RFBs) under subzero temperature is of great significance for the use of renewable energy in cold regions. However, RFBs are generally used above 10 °C. Herein we present non-aqueous organic RFBs based on 5,10,15,20-tetraphenylporphyrin (H TPP) as a bipolar redox-active material (anode: [H TPP] /H TPP, cathode: H TPP/[H TPP] ) and a Y-zeolite-poly(vinylidene fluoride) (Y-PVDF) ion-selective membrane with high ionic conductivity as a separator. The constructed RFBs exhibit a high volumetric capacity of 8.72 Ah L with a high voltage of 2.83 V and excellent cycling stability (capacity retention exceeding 99.98 % per cycle) in the temperature range between 20 and -40 °C. Our study highlights principles for the design of RFBs that operate at low temperatures, thus offering a promising approach to electrochemical energy storage under cold-climate conditions.

Copper Porphyrin as a Stable Cathode for High‐Performance Rechargeable Potassium Organic Batteries

“…CuDEPP showed very limited solubility in common solvents, such as propylene carbonate (PC) and dimethyl carbonate (DMC), and no color change was seen if CuDEPP was placed in these solvents, a prerequisite for a stable electrode material in liquid‐electrolyte‐based rechargeable batteries. The electrochemical redox chemistry of the CuDEPP electrode material is supposed to be a reversible oxidation and reduction of the aromatic porphyrins (18 π) with the formation of a dicationic species (16 π) and a dianionic species (20 π) because of the bipolar properties of the porphyrin molecule, in which in total four electrons can be transferred easily in the highly conjugated porphyrin macrocycle . As a result of the bipolar redox‐active properties, the electrochemical processes of CuDEPP in a KIB are proposed in Scheme a.…”

“…Moreover, porphyrin‐derived materials have unique merits such as insolubility and high electronic conductivity, which render them promising candidates as high‐performance organic cathode materials. It was proven that porphyrins could serve as bipolar organic electrodes by donating or accepting electrons at its macrocyclic core to realize multiple electron transfer to provide both high energy and high power density within one system . Recently, porphyrin‐based COF and MOF materials were investigated for EES, which suggests new organic compounds for high‐performance energy storage.…”

Bioderived Molecular Electrodes for Next‐Generation Energy‐Storage Materials

“…Similarly, a typical zinc–air battery was also demonstrated with a cobalt‐based porphyrin covalent organic framework, which delivered an operating voltage of 0.71 V and an initial discharge capacity of 772.7 mAh g −1 , and excellent durability of over 200 cycles at a current density of 2 mA cm −2 . Finally, porphyrin‐based material 27 was also employed as a bipolar redox‐active material for batteries . The CV results for 27 displayed four reversible one‐electron‐transfer reactions and the stability of the molecule at different redox states was studied by using HOMO/singly occupied molecular orbital (SOMO) diagrams (Figure ).…”

New Organic Electrode Materials for Ultrafast Electrochemical Energy Storage

“…In addition, due to their small highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) gaps that enable fast electron uptake and release, porphyrins exhibit high redox activities and can be potentially used for EES devices. Recently, porphyrin‐based active materials have drawn great interest as new class of organic electrodes for supercapacitors, rechargeable batteries, and redox‐flow batteries . Low conductivity and high solubility in the organic electrolyte are generally two main drawbacks of organic electrode materials .…”

“…Despite the interesting redox chemistries, most of porphyrins are soluble in organic solvents, which limit their usage as electrode materials. In fact, 5,10,15,20‐tetraphenylporphyrin (H2TPP) has been recently demonstrated to be used as the active material for redox‐flow batteries . In contrast, the CuDEPP with two ethynyl substituents has a low solubility.…”