A polyoxometalate redox flow battery: functionality and upscale

Abstract

While redox flow batteries carry a large potential for electricity storage, specifically for regenerative energies, the current technology-prone system—the all-vanadium redox flow battery—exhibits two major disadvantages: low energy and low power densities. Polyoxometalates have the potential to mitigate both effects. In this publication, the operation of a polyoxometalate redox flow battery was demonstrated for the polyoxoanions [SiW12O40]4– (SiW12) in the anolyte and [PV14O42]9– (PV14) in the catholyte. Emphasis was laid on comparing to which extent an upscale from 25 to 1400 cm2 membrane area may impede efficiency and operational parameters. Results demonstrated that the operation of the large cell for close to 3 months did not diminish operation and the stability of polyoxometalates was unaltered.

Redox Flow Batteries: Materials, Design and Prospects

“…Table 3 shows that the number of publications in recent years, since 2013, on RFBs based on POMs is very limited. With the exception of Friedl et al in 2019 [125], the remaining studies show, generally, a low cell area compared to what has been reported in VRFBs (≤5 cm 2 ). Furthermore, although there are some interesting efficiency values, the current densities are still low.…”

“…The interaction of the redox centers of the POMs is generally reduced due to their large sizes [3] and the electrons added by reduction to the POMs are not allocated to a specific atom, therefore allowing for fast kinetics and high-power densities [122,123]. Moreover, the large size of the POMs, which range from 6 to 25Ȧ [124], along with the electrostatic repulsion, do not allow the permeation through the actual RFBs' commercial cation exchange membranes (CEM), preventing cross-over and mixing of the active species [125]. The interest in applying POMs to RFBs is vast and is still at an infant stage.…”

“…The species are chosen based on the redox potentials to ensure that they intervene in the chemical reduction and oxidation of the solid components. This strategy allows for low viscosity, a high charging rate, and a high energy density [125].…”

Molecular Vanadium Oxides for Energy Conversion and Energy Storage: Current Trends and Emerging Opportunities

“…[80] This also illustrates the advantages of using two independent electrolytes in asymmetric RFBs,a st he anolyte and catholyte can be adjusted individually to achieve an optimized whole-cell performance.I n addition, Stimming and co-workers observed by 51 VN MR spectroscopy that, upon degradation, the [PV 14 O 42 ] 9À cluster reassembled under operational conditions.T his behavior could lead to significantly longer operational lifetimes for POM-based RFBs compared to other RFB systems. [76,81] The POM/POVsystem has also recently been successfully scaledup and operated in ap ilot-scale reactor. [81] These studies demonstrate the scalability and advantages of aqueous POM/ POVRFBs.…”

The Intrinsic Charge Carrier Behaviors and Applications of Polyoxometalate Clusters Based Materials

“…DOI: 10.1002/adma.202005019 charge carrier behaviors, which allows POMs to display unparalleled physical and chemical properties compared to traditional metal oxides. [2] In this regard, the intrinsic charge carrier behavior of POM-based materials is undoubtedly the cornerstone for their diverse applications in molecular electronics, [20][21][22][23][24][25][26][27][28][29] solar cells, [30][31][32][33] redox flow batteries, [34][35][36][37][38][39][40][41] and molecular-cluster batteries. [42][43][44][45] The charge carrier behaviors of POM-based materials are present on two levels.…”